Contra Costa County, California

Last updated

Contra Costa County
Martinez, CA USA - panoramio (1).jpg
Images, from left to right: Contra Costa County courthouse, Mount Diablo's North Peak
Seal of Contra Costa County, California.png
Contra Costa County, California
Interactive map of Contra Costa County
Map of California highlighting Contra Costa County.svg
Location in the state of California
CountryUnited States
State California
Region San Francisco Bay Area
Incorporated February 18, 1850 [1]
Named for "Opposite coast" (Spanish: Contra costa) of the San Francisco Bay
County seat Martinez
Largest city Concord (population and land area)
Richmond (total area)
  Type Council–CAO
  Body Board of Supervisors
  ChairJohn Gioia
  Vice ChairFederal D. Glover
  Board of Supervisors [2]
  • John Gioia
  • Candace Andersen
  • Diane Burgis
  • Ken Carlson
  • Federal D. Glover
  County Administrator Office [3] Monica Nino
  Total804 sq mi (2,080 km2)
  Land715.94 sq mi (1,854.3 km2)
  Water81 sq mi (210 km2)
Highest elevation
3,852 ft (1,174 m)
  Density1,629/sq mi (629/km2)
Gross Domestic Product
  TotalUS$76.341 billion (2022)
Time zone UTC−8 (Pacific Time Zone)
  Summer (DST) UTC−7 (Pacific Daylight Time)
Area code 510, 341, 925
FIPS code06-013
GNIS feature ID 1675903
Congressional districts 8th, 9th, 10th

Contra Costa County ( /ˌkɒntrəˈkɒstə/ ; Contra Costa, Spanish for "Opposite Coast") is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. As of the 2020 United States Census, the population was 1,165,927. [6] The county seat is Martinez. [7] [8] It occupies the northern portion of the East Bay region of the San Francisco Bay Area and is primarily suburban. The county's name refers to its position on the other side of the bay from San Francisco. [9] Contra Costa County is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area.




In prehistoric times, particularly the Miocene epoch, portions of the landforms now in the area (then marshy and grassy savanna) were populated by a wide range of now extinct mammals, known in modern times by the fossil remains excavated in the southern part of the county. In the northern part of the county, significant coal and sand deposits were formed in even earlier geologic eras. Other areas of the county have ridges exposing ancient but intact (not fossilized) seashells, embedded in sandstone layers alternating with limestone. Layers of volcanic ash ejected from geologically recent but now extinct volcanoes, compacted and now tilted by compressive forces, may be seen at the site of some road excavations. This county is an agglomeration of several distinct geologic terranes, as is most of the greater San Francisco Bay Area, which is one of the most geologically complex regions in the world. The great local mountain Mount Diablo has been formed and continues to be elevated by compressive forces resulting from the action of plate tectonics and at its upper reaches presents ancient seabed rocks scraped from distant oceanic sedimentation locations and accumulated and lifted by these great forces. Younger deposits at middle altitudes include pillow lavas, the product of undersea volcanic eruptions.

Native American period

There is an extensive but little-recorded human history of pre-European settlement in this area, with the present county containing portions of regions populated by a number of Native American tribes. The earliest definitively established occupation by modern man ( Homo sapiens ) appears to have occurred six to ten thousand years ago. However, there may have been human presence far earlier, at least as far as nonsettling populations are concerned. The known settled populations were hunter-gatherer societies that had no knowledge of metals and that produced utilitarian crafts for everyday use (especially woven reed baskets) of the highest quality and with graphic embellishments of great aesthetic appeal. Extensive trading from tribe to tribe transferred exotic materials such as obsidian (useful for the making of arrowheads and other stone tools) throughout the region from far distant Californian tribes. Unlike the nomadic Native American of the Great Plains it appears that these tribes did not incorporate warfare into their culture but were instead generally cooperative. Within these cultures the concept of individual or collective land ownership was nonexistent. Early European settlers in the region, however, did not record much about the culture of the natives. Most of what is known culturally comes from preserved contemporaneous and excavated artifacts and from inter-generational knowledge passed down through northerly outlying tribes of the larger region.

Spanish colonial

Early interaction of these Native Americans with Europeans came with the Spanish colonization via the establishment of missions in this area, with the missions in San Jose, Sonoma, and San Francisco and particularly the establishment of a Presidio (a military establishment) in 1776. Although there were no missions established within this county, Spanish influence here was direct and extensive, through the establishment of land grants from the King of Spain to favored settlers.

Mexican land grants

Don Salvio Pacheco Salvio Pacheco.jpg
Don Salvio Pacheco
Don Victor Castro Don Victor Castro.jpg
Don Víctor Castro

In 1821 Mexico gained independence from Spain. While little changed in ranchero life, the Mexican War of Independence resulted in the secularization of the missions with the re-distribution of their lands, and a new system of land grants under the Mexican Federal Law of 1824. Mission lands extended throughout the Bay Area, including portions of Contra Costa County. Between 1836 and 1846, during the era when California was a province of independent Mexico, the following 15 land grants were made in Contra Costa County. [10]

The smallest unit was one square league, or about seven square miles, or 4,400 acres (17.8 square kilometers), maximum to one individual was eleven leagues, or 48,400 acres (195.9 km2), including no more than 4,428 acres (17.9 km2) of irrigable land. Rough surveying was based on a map, or diseño, measured by streams, shorelines, and/or horseman who marked it with rope and stakes. Lands outside rancho grants were designated el sobrante, as in surplus or excess, and considered common lands. The law required the construction of a house within a year. Fences were not required and were forbidden where they might interfere with roads or trails. Locally a large family required roughly 2000 head of cattle and two square leagues of land (fourteen square miles) to live comfortably. Foreign entrepreneurs came to the area to provide goods that Mexico could not, and trading ships were taxed. [note 1]

Much of Rancho Los Meganos is now part of Marsh Creek State Park. The John Marsh Stone House still stands, but is in need of restoration. Historic American Buildings Survey Gleason Collection - S.F. College for Women Taken about- 1870 TOWER RESTORED AFTER EARTHQUAKE OF 1868 - John Marsh House, Marsh Creek Road, HABS CAL,7-BRENT.V,1-2.tif
Much of Rancho Los Meganos is now part of Marsh Creek State Park. The John Marsh Stone House still stands, but is in need of restoration.

Bear Flag Republic and statehood

The exclusive land ownership in California by the approximate 9,000 [11] Hispanics in California would soon end. John Marsh, owner of Rancho Los Meganos in Contra Costa County, had a lot to do with this. He sent letters to influential people in the eastern United States extolling the climate, soil, and potential for agriculture in California, with the deliberate purpose of encouraging Americans to immigrate to California and lead to its becoming part of the United States. He succeeded. His letters were published in newspapers throughout the East and started the first wagon trains rolling toward California. He also invited them to stay on his ranch until they could get settled, so the Rancho Los Meganos became the terminus of the California trail. [12]

This led to the Bear Flag Revolt in 1846 when about 30 settlers originally from the United States declared a republic in June 1846 and were enlisted and fighting under the U.S. flag by July 1846. Following the Mexican–American War of 1846–48, California was controlled by U.S. settlers organized under the California Battalion and the U.S. Navy's Pacific Squadron. After some minor skirmishes, California was under U.S. control by January 1847 and formally annexed and paid for by the U.S. in 1848. By 1850, California's population of over 100,000 was rapidly growing due to the gold rush and the large amount of gold being exported east, which gave California enough clout to choose its own boundaries, write its own constitution, and be admitted to the Union as a free state in 1850 without going through territorial status as required for most other states.

In 1850 California had a non-Indian population of over 100,000. [13] The number of Indians living in California in 1850 has been estimated to be from 60,000 to 100,000. By 1850 the Mission Indian populations had largely succumbed to disease and abuse and only numbered a few thousand. California's 1852 state Census gives 31,266 Indian residents, but this is an under-count since there was little incentive and much difficulty in getting it more correct. [14]

County creation

Postcard showing the Contra Costa County Courthouse in 1906. 06903-Martinez-1906-Courthouse of Contra Costa Co.-Bruck & Sohn Kunstverlag.jpg
Postcard showing the Contra Costa County Courthouse in 1906.

Contra Costa County was one of the original 27 counties of California, created in 1850 at the time of statehood. The county was originally to be called Mt. Diablo County, but the name was changed prior to incorporation as a county. The county's Spanish language name means opposite coast, because of its location opposite San Francisco, in an easterly direction, on San Francisco Bay. Southern portions of the county's territory, including all of the bayside portions opposite San Francisco and northern portions of Santa Clara County, were given up to form Alameda County effective March 25, 1853.

The land titles in Contra Costa County may be traced to multiple subdivisions of a few original land grants. The grantee's family names live on in a few city and town names such as Martinez , Pacheco and Moraga and in the names of streets, residential subdivisions, and business parks. A few mansions from the more prosperous farms have been preserved as museums and cultural centers and one of the more rustic examples has been preserved as a working demonstration ranch, Borges Ranch.

In the 1860 United States Census, Contra Costa County had a population of 4,381. [15]


During World War II, Richmond hosted one of the two Bay Area sites of Kaiser Shipyards and wartime pilots were trained at what is now Concord/Buchanan Field Airport. Additionally, a large Naval Weapons Depot and munitions ship loading facilities at Port Chicago remain active to this day, but with the inland storage facilities recently declared surplus, extensive redevelopment is being planned for this last large central-county tract. The loading docks were the site of a devastating explosion in 1944. Port Chicago was bought out and demolished by the Federal Government to form a safety zone near the Naval Weapons Station loading docks. At one time the Atlas Powder Company (subsequently closed) produced gunpowder and dynamite. The site of the former Atlas Powder Company is located at Point Pinole Regional Shoreline, [16] part of the East Bay Regional Parks District. [17]

1945-present day

With the postwar baby boom and the desire for suburban living, large tract housing developers would purchase large central county farmsteads and develop them with roads, utilities and housing. Once mostly rural walnut orchards and cattle ranches, the area was first developed as low-cost, large-lot suburbs, with a typical low-cost home being placed on a "quarter-acre" (1,000 m2) lot actually a little less at 10,000 square feet (930 square metres). Some of the expansion of these suburban areas was clearly attributable to white flight from decaying areas of Alameda County and the consolidated city-county of San Francisco, but much was due to the postwar baby boom of the era creating demand for three- and four-bedroom houses with large yards that were unaffordable or unavailable in the established bayside cities.

A number of large companies followed their employees to the suburbs, filling large business parks. The establishment of a large, prosperous population in turn fostered the development of large shopping centers and created demand for an extensive supporting infrastructure including roads, schools, libraries, police, firefighting, water, sewage, and flood control.

The establishment of the Bay Area Rapid Transit (BART) system, the modernization of Highway 24, and the addition of a fourth Caldecott Tunnel bore all served to reinforce the demographic and economic trends in the Diablo Valley area, with cities such as Walnut Creek and Concord becoming edge cities.

The central county cities have in turn spawned their own suburbs within the county, extending east along the county's estuarine north shore; with the older development areas of Bay Point and Pittsburg being augmented by extensive development in Antioch, Oakley, and Brentwood.

The effects of the housing value crash (2008–2011) varied widely throughout the county. Values of houses in prosperous areas with good schools declined only modestly in value, while houses recently built in outlying suburbs in the eastern part of the county experienced severe reductions in value, accelerated by high unemployment and consequent mortgage foreclosures, owner strategic walk-aways, and the too-rapid conversion of neighborhoods from owner-occupancy to rentals. Home values rebounded as the economy recovered from the recession.


According to the U.S. Census Bureau, the county has a total area of 804 square miles (2,080 km2), of which 716 square miles (1,850 km2) is land and 88 square miles (230 km2) (11%) is water. [18]

Contra Costa County's physical geography is dominated by the bayside alluvial plain, the Oakland Hills Berkeley Hills, several inland valleys, and Mount Diablo, an isolated 3,849-foot (1,173 m) upthrust peak at the north end of the Diablo Range of hills. The summit of Mount Diablo is the origin of the Mount Diablo Meridian and Base Line, on which the surveys of much of California and western Nevada are based.

The Hayward Fault Zone runs through the western portion of the county, from Kensington to Richmond. The Calaveras Fault runs in the south-central portion of the county, from Alamo to San Ramon. The Concord Fault runs through part of Concord and Pacheco, and the Clayton-Marsh Creek-Greenville Fault runs from Clayton at its north end to near Livermore. These strike-slip faults and the Diablo thrust fault near Danville are all considered capable of significantly destructive earthquakes and many lesser related faults are present in the area that cross critical infrastructure such as water, natural gas, and petroleum product pipelines, roads, highways, railroads, and BART rail transit.


Contra Costa County is broadly divided into three sub-areas: [19]

Adjacent counties

National protected areas

Mount Diablo

Mount Diablo from Shell Ridge Open Space Mount Diablo from Quarry Hill in Shell Ridge Open Space.jpg
Mount Diablo from Shell Ridge Open Space

The most notable natural landmark in the county is the 3,849-foot (1,173 m) Mount Diablo, at the northerly end of the Diablo Range. Mount Diablo and its neighboring North Peak are the centerpiece of Mt. Diablo State Park (MDSP), created legislatively in 1921 and rededicated in 1931 after land acquisitions had been completed. At the time this park comprised a very small portion of the mountain.

In the 1960s, suburban development expanding from the surrounding valleys began to threaten the open space of the mountain. In 1971, MDSP consisted of 6,788 acres (27.5 km2). That year, concerned residents formed the non-profit organization Save Mount Diablo to raise funds and awareness to protect more open space. In addition to encouraging acquisition by the state and local authorities, SMD started fundraising and acquiring properties to transfer to the park. MDSP was the first of twenty-nine Diablo-area parks and preserves that have been created around the peaks; today these preserves protect more than 89,000 acres (360 km2).

These Diablo public lands stretch southeast and include the Concord Naval Weapons Station, Shell Ridge Open Space and Lime Ridge Open Spaces near Walnut Creek, to the State Park, and east to the Los Vaqueros Reservoir watershed and four surrounding East Bay Regional Park District preserves, including Morgan Territory Regional Preserve, Brushy Peak Regional Preserve, Vasco Caves Regional Preserve, and Round Valley Regional Preserve. The new Marsh Creek State Park, formerly known as Cowell Ranch State Park, and Black Diamond Mines Regional Preserve, are among the open spaces that stretch to the north. The open spaces controlled by cities, the East Bay Regional Park District, Mount Diablo State Park, and various regional preserves now adjoin and protect most of the elevated regions of the mountain.

The name Mount Diablo is said to originate from an incident involving Spanish soldiers who christened a thicket as Monte del Diablo when natives they were pursuing apparently disappeared into the thicket. Anglo settlers later misunderstood the use of the word 'monte' (which can mean 'mountain', or 'thicket'), and applied the name to the most obvious local landmark.

According to the Contra Costa Times, in 2011, there were rumors that Contra Costa County was going to rename the mountain as "Mt. Ronald Reagan" or "Mt. Reagan", after the former US President and California governor. Residents have generated multiple petitions to change the name of the mountain, one in 2005 and another in 2011, but these were not successful.


Historical population
1860 5,328
1870 8,46158.8%
1880 12,52548.0%
1890 13,5157.9%
1900 18,04633.5%
1910 31,67475.5%
1920 53,88970.1%
1930 78,60845.9%
1940 100,45027.8%
1950 298,984197.6%
1960 409,03036.8%
1970 558,38936.5%
1980 656,38017.5%
1990 803,73222.4%
2000 948,81618.1%
2010 1,049,02510.6%
2020 1,165,92711.1%
U.S. Decennial Census [20]
1790–1960 [21] 1900–1990 [22]
1990–2000 [23] 2010 [24] 2020 [25]

2020 census

Contra Costa County, California - Demographic Profile
(NH = Non-Hispanic)
Race / EthnicityPop 2010 [24] Pop 2020 [25] % 2010% 2020
White alone (NH)500,923455,42147.75%39.06%
Black or African American alone (NH)93,60497,9948.92%8.40%
Native American or Alaska Native alone (NH)2,9842,5530.28%0.22%
Asian alone (NH)148,881214,52014.19%18.40%
Pacific Islander alone (NH)4,3825,7200.42%0.49%
Some Other Race alone (NH)3,1228,3660.30%0.72%
Mixed Race/Multi-Racial (NH)39,56966,4533.77%5.70%
Hispanic or Latino (any race)255,560314,90024.36%27.01%

Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos can be of any race.


Ethnic origins in Contra Costa County Ethnic Origins in Contra Costa County, CA.png
Ethnic origins in Contra Costa County

Places by population, race, and income

2010 Census

The 2010 United States Census reported that Contra Costa County had a population of 1,049,025. The racial makeup of Contra Costa County was 614,512 (58.6%) White; 97,161 (9.3%) African American; 6,122 (0.6%) Native American; 151,469 (14.4%) Asian (4.6% Filipino, 3.8% Chinese, 2.1% Indian); 4,845 (0.5%) Pacific Islander; 112,691 (10.7%) from other races; and 62,225 (5.9%) from two or more races. There were 255,560 people (24.4%) of Hispanic or Latino ancestry, of any race; 17.1% of Contra Costa County's population was of Mexican ancestry, while 1.9% was of Salvadoran heritage. [33]


As of the census [35] of 2000, there were 948,816 people, 344,129 households, and 242,266 families residing in the county. The population density was 1,318 inhabitants per square mile (509/km2). There were 354,577 housing units at an average density of 492 per square mile (190/km2).

Of residents who identified with European ethnicities, 9.0% were German, 7.7% Irish, 7.3% English, and 6.5% Italian ancestry according to Census 2000. 74.1% spoke English, 13.1% Spanish, and 2.6% Tagalog.

By 2005, 53.2% of Contra Costa County's population were non-Hispanic whites. African Americans made up 9.6% of the population, while ethnic Asians constituted 13.1%. Latinos, representing people of Spanish, Portuguese, indigenous and mestizo populations of the Western hemisphere, comprised 21.1% of the county population.

In 2000, there were 344,129 households, out of which 35.4% had children under the age of 18 living with them, 54.5% were married couples living together, 11.5% had a female householder with no husband present, and 29.6% were non-families. 22.9% of all households were made up of individuals, and 8.00% had someone living alone who was 65 years of age or older. The average household size was 2.72 and the average family size was 3.23.

In the county, the population was spread out, with:

The median age was 36 years. For every 100 females there were 95.4 males. For every 100 females age 18 and over, there were 92.2 males.

The median income for a household in the county was $63,675, and the median income for a family was $73,039 (these figures had risen to $75,483 and $87,435 respectively as of a 2007 estimate). [36]

Males had a median income of $52,670 versus $38,630 for females. The per capita income for the county was $30,615. About 5.4% of families and 7.6% of the population were below the poverty line, including 9.8% of those under age 18 and 6.0% of those age 65 or over.

In 2000, the largest denominational groups were Catholics (with 204,070 adherents) and Evangelical Protestants (with 74,449 adherents). [37] The largest religious bodies were the Catholic Church (with 204,070 members) and The Baptist General Conference (with 24,803 members). [38] The Rohr Jewish Learning Institute teaches courses in the county. [39]


Since 1932, Contra Costa County has been a Democratic stronghold in presidential elections. It temporarily leaned toward the Republican Party in the 1970s and 1980s, with successive presidential wins by Richard Nixon in 1972, Gerald Ford in 1976, and Ronald Reagan in 1980 and 1984. Reagan was the last Republican presidential candidate to win the county.

United States presidential election results for Contra Costa County, California [40]
Year Republican Democratic Third party
2020 152,87726.30%416,38671.63%12,0532.07%
2016 115,95624.51%319,28767.50%37,7717.99%
2012 136,51731.09%290,82466.23%11,8042.69%
2008 136,43630.10%306,98367.73%9,8252.17%
2004 150,60836.46%257,25462.28%5,1661.25%
2000 141,37337.06%224,33858.81%15,7674.13%
1996 123,95435.15%196,51255.73%32,1369.11%
1992 112,96529.51%194,96050.93%74,89819.56%
1988 158,65247.86%169,41151.10%3,4481.04%
1984 172,33154.48%140,99444.57%2,9930.95%
1980 144,11250.12%107,39837.35%36,03512.53%
1976 126,59849.35%123,74248.24%6,1942.41%
1972 139,04454.13%111,71843.49%6,1222.38%
1968 97,48644.53%101,66846.44%19,7639.03%
1964 65,01136.47%113,07163.44%1630.09%
1960 82,92246.82%93,62252.86%5790.33%
1956 74,97150.98%71,73348.78%3470.24%
1952 70,09449.61%70,41649.84%7860.56%
1948 36,95840.45%50,27755.02%4,1414.53%
1944 26,81635.86%47,83163.96%1380.18%
1940 18,62737.22%30,90061.75%5131.03%
1936 9,60426.70%26,00772.29%3641.01%
1932 10,90737.33%17,21858.94%1,0893.73%
1928 13,49560.38%8,57338.36%2811.26%
1924 9,06154.67%1,1146.72%6,39838.60%
1920 9,04163.75%3,48324.56%1,65811.69%
1916 5,73144.05%6,09246.82%1,1889.13%
1912 400.48%3,29039.40%5,02060.12%
1908 3,33660.61%1,59929.05%56910.34%
1904 2,83362.55%1,25727.75%4399.69%
1900 2,16557.02%1,54940.80%832.19%
1896 1,83456.10%1,38142.25%541.65%
1892 1,63151.79%1,33242.30%1865.91%
1888 1,51855.04%1,17742.68%632.28%
1884 1,49655.86%1,11441.60%682.54%
1880 1,30256.31%1,01043.69%00.00%

In the United States House of Representatives, Contra Costa County is split among three congressional districts: [41]

In the State Assembly, Contra Costa County is split among four districts:

In the State Senate, the county is split among three districts:

Democrats hold wide advantages in voter registration numbers in all political subdivisions in Contra Costa County. The Democrats' largest registration advantage in Contra Costa is in the cities of Richmond, where there is a 60.3% registration advantage with 3,192 Republicans (6.2%) out of 51,395 registered voters compared to 34,159 Democrats (66.5%) and 12,095 voters who have no party preference (23.5%); El Cerrito, where there is a 59.0% registration advantage with 1,169 Republicans (7.4%) out of 15,877 registered voters compared to 10,543 Democrats (67.6%) and 3,654 voters who have no party preference (23.0%); and San Pablo, where there is a 58.3% registration advantage with 641 Republicans (6.1%) out of 10,550 registered voters compared to 6,793 Democrats (64.4%) and 2,746 voters who have no party preference (26.0%).

Voter registration statistics

Cities by population and voter registration


The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense.

Cities by population and crime rates (2019)

Cities by population and crime rates (2019)
CityPopulation [46] Violent crimes [46] Violent crime rate
per 1,000 persons
Property crimes [46] Property crime rate
per 1,000 persons
Antioch 112,6416485.753,19928.4
Brentwood 65,4831662.541,33520.39
Clayton 12,35610.0815512.54
Concord 130,6155414.144,56034.91
Danville 44,997230.512966.58
El Cerrito 25,8571525.881,30050.28
Hercules 25,789311.234113.22
Lafayette 26,87240.1535813.32
Martinez 38,692832.1557014.73
Moraga 17,908231.281246.92
Oakley 43,014511.1949711.55
Orinda 20,071170.851959.72
Pinole 19,439593.0486644.55
Pittsburg 73,6374466.061,66022.54
Pleasant Hill 35,125882.511,48442.25
Richmond 110,9881,0349.324,18837.73
San Pablo 31,3361946.191,00932.2
San Ramon 84,605580.691,09912.99
Walnut Creek 70,5461201.72,49635.38



The great rancheros of the Spanish period were divided and sold for agricultural uses, with intensively irrigated farming made possible in some areas by the development of canals that brought water from the eastern riverside portions of the county to the central portion. Other areas could use the more limited water available from local creeks and from wells. Orchards dominated where such water was available, while other, seasonally dry areas were used for cattle ranching. In central parts of the county walnuts were an especially attractive orchard crop, using the thin-shelled English Walnut branches grafted to the hardy and disease-resistant American Walnut root stock. In the Moraga region, pears dominated, and many old (but untended) roadside trees are still picked seasonally by passers-by. In eastern county, stone fruit, especially cherries, is still grown commercially, with seasonal opportunities for people to pick their own fruit for a modest fee.

Irrigation canals

The Contra Costa Canal, a concrete-lined and fenced irrigation canal still makes a loop through central county and provided industrial and agricultural grade water to farms and industry. While no longer used for extensive irrigation, it is still possible for adjoining landowners (now large suburban lot owners) to obtain pumping permits. Most of this water is destined for the heavy industry near Martinez. As with the railroad rights of way there is now an extensive public trail system along these canals.

Commuter railroads

The development of commuter railroads proceeded together with the subdivision of farms into parcels. In some cases, such as the development of Saranap, the same developer controlled both the railroad (Sacramento Northern) and the development. These early suburbanization developments were an extension of the earlier development of trolley car suburbs in what are now considered the highly urban environments of the near East Bay.

Heavy industry

View of the Shell Martinez oil refinery ShellMartinez-refi.jpg
View of the Shell Martinez oil refinery

Owing to its extensive waterfront on San Francisco, San Pablo, and Suisun bays the northwestern and northern segments have long been sites for heavy industry, including a number of still active oil refineries (particularly Chevron in Richmond, Phillips 66 in Rodeo, Shell Oil (now PBF) and Tesoro (now Marathon)- in Martinez), chemical plants (Dow Chemical) and a once substantial integrated steel plant, United States Steel, now reduced to secondary production of strip sheet and wire. The San Joaquin River forms a continuation of the northern boundary turns southward to form the eastern boundary of the county. Some substantial Sacramento-San Joaquin Delta "islands" (actually leveed former marshes) are included in this corner of the county.


West County

The West County is the area near or on San Francisco and San Pablo bays. The housing stock in the region was extensively developed after the great San Francisco earthquake of 1906. Much of the housing stock in these areas is becoming quite expensive. As an alternative to moving to either the expensive central county, or the too-distant East County, this area is becoming gentrified, with a mix of races and income levels a character actively sought by some housing purchasers. The downside of this is a corresponding lack of affordable housing for those working lower-paying service jobs a problem endemic throughout the region. There has recently been a housing boom or tract housing in Richmond and also in the Hercules areas. These gentrifying areas are the most diverse in Contra Costa County. [ citation needed ]

Central county

Central county scene — Mount Diablo, Concord, Pleasant Hill, and Walnut Creek

The central part of the county is a valley traversed by Interstate 680 and Highway 24. The towns east of the hills, on or near Highway 24 and their surrounding areas (Lafayette, Moraga and Orinda) are collectively known as Lamorinda. The major central county cities along Interstate 680 are Martinez, Concord, Pleasant Hill, Walnut Creek, Danville, San Ramon, and unincorporated Alamo. Owing to the high quality of its public schools (due largely to both demographics and added support from prosperous parents), this area has become a magnet for welloff families with children. During the real estate boom, housing prices were driven to astounding levels. From 2007, home prices in the region have seen substantial decreases and the affordability rate has risen. During the real estate boom, the high price of homes and scarcity of land resulted in many speculators purchasing older, smaller homes and partially or completely tearing them down to construct larger homes.

In this way the central county region has become a mix of older suburbs, newer developments, small lot "infill" developments, and extensive shopping areas.

Lafayette Reservoir Lafayette Reservoir.JPG
Lafayette Reservoir

East County

Lower cost modern tract developments continue along Suisun Bay in the "East County" towns of Pittsburg, Antioch, and Oakley - new "bedroom" communities" to serve the now "edge cities". The median income of a family in the two relatively affluent East County towns of Brentwood and Discovery Bay is approaching $100k/yr. placing them in the top fifteen percent of affluent towns in the United States. California Distinguished Schools, golf courses, vineyards, and upscale homes are found in Brentwood and Discovery Bay. Discovery Bay is based on a waterfront community of 3,500+ homes with private docks with access to the Sacramento-San Joaquin River Delta. Discovery Bay also features gated and non-gated "off-water" communities with homes from 1,400 square feet (130 square metres) up to 4,700 square feet (440 square metres).

From 2010 to 2018 Highway 4 underwent multimillion-dollar improvements from that added lanes through Brentwood, Antioch and Pittsburg to reduce driving time between East County and Concord/Walnut Creek, as this commute at one time was the 10th worst in the nation. [47] Vasco Road is also an important link between East County/Brentwood and Livermore. Additionally, a county road from Brentwood to Tracy has received Federal Funds to be upgraded to a highway link between the areas. [48]

County budget problems

Across 30 years, two forces combined to create county budget problems, peaking in 2008. First, rather than compensate police, medical, and firefighting personnel directly, health and retirement benefits were granted without proper actuarial examination, leading to unexpected but predictable high costs as personnel aged and ultimately retired with continued "first class" health and retirement benefits. Second, the collapse of the "housing bubble" enabled purchasers of distressed properties — many of which were owned by banks and other mortgage holders — to petition for lower property assessments, in many cases reducing by half the revenue to the county for specific parcels. Continuing downturns in employment prospects further increased the needs for various social services. These deficits and demands, combined with a lack of support from a similarly stressed California state government and the United States Federal government, required county supervisors and service providers to allocate limited resources in a time of increasing demand. The projected budget deficit was $45 million as of early 2011. [49] Perhaps more significantly, the total unfunded liability for retiree benefits is $2.4 billion. [50]

Technical innovators

In the 1970s and 1980s, many small and innovative technical firms started in Contra Costa. Most of these are no longer present, either failing, being absorbed into larger corporations, or outgrowing their original location and moving elsewhere in the Bay Area. [ citation needed ]

Corporate headquarters

By the early 1990s, 22 million square feet of office space had been built [51] along the 680 corridor, that segment of Interstate Highway 680 that extends from Concord in the north to San Ramon in the south, continuing into inland Alameda County from Dublin to Pleasanton. During the 1980s and early 1990s, many corporations that were formerly housed in the more central metropolitan area followed their employees by moving to these large suburban and edge city office areas and office parks.[ citation needed ]


There are currently political fights over the potential redevelopment of the county seat (Martinez), with long-term residents and many elsewhere in the county concerned that it will lose its remaining small-town charm and utility in an effort to become more like the county's major recreational shopping center of Walnut Creek.[ citation needed ]

The inland portions of the Concord Naval Weapons Station have been declared surplus by the Federal government and this area is expected to provide what is likely the last opportunity to plan and build city-sized development within the central county.[ citation needed ] This area will become a portion of the city of Concord, and planners expect that development will be confined to the lower and flatter portions of the depot, with the remainder becoming a substantial addition to the county's open space. Much of the land to be developed is relatively flat grassland and the most prominent structures are ammunition bunkers that will be removed, so future uses of the property are largely unconstrained by previous uses. [52]


The Contra Costa County Library is the county's library system.


Contra Costa County receives media from the rest of the Bay Area.

The City of Concord is served by the daily newspaper, the East Bay Times published by the Bay Area News Group-East Bay (part of the Media News Group, Denver, Colorado), with offices in Walnut Creek. The paper was originally a paper run and owned by the Lesher family. Since the death of Dean Lesher in 1993, the paper has had several owners. [53] The publisher also issues weekly local papers, such as the Concord Transcript, which is the local paper for Concord and nearby Clayton.

In December 2019, there was a flurry of reports from reliable sources including the Associated Press and the San Francisco Chronicle that the 161-year-old Martinez News-Gazette, one of the longest-running newspapers in California, may have to cease publication. But as of late May 2020, the threatened cessation did not materialize and the newspaper appears to have weathered that storm. The newspaper did cease publication of a print edition effective April 2, 2020, but this was characterized as a temporary measure arising from a lack of advertising revenue. Since March 2020, this in turn arose as many local businesses were forced to suspended operations or even ceased to exist, when the area was under shelter-in-place regulations arising from COVID-19 pandemic. The newspaper plans to resume a full print edition when the local shelter-in-place restrictions are lifted. [54]


Prior to 1903, most travel to central Contra Costa County was by boat or rail to Martinez on the northern waterfront and from there to the industrial areas east along the waterfront as well as farming regions to the south.

In 1903, the first tunnel through the Oakland hills (now Old Tunnel Road) was built, principally as a means of bringing hay by horse-, mule-, or ox-drawn wagons from central and eastern agricultural areas to feed the draft animals that provided the power to public and private transportation in the East Bay at the time. The tunnel exited in the hills high above the crossroads of Orinda with the road continuing on to Lafayette, Walnut Creek, and Danville. The road was just wide enough for one car in each direction and had no shoulders.

In 1937, the two-bore Caldecott Tunnel for road vehicles was completed, making interior Contra Costa County much more accessible. After World War II, the tunnels allowed waves of development to proceed, oriented toward Oakland rather than the northern shoreline, and the northern shoreline cities began to decline. The tunnel has since been augmented with a third bore, completed in 1964, and a fourth, completed in 2013.

Major highways

Mass transit


The county has two general aviation airports:

JetSuiteX provides four times weekly service from Concord Airport (CCR) to Las Vegas, Burbank, and Santa Ana.


The western termini of several original transcontinental railroad routes have been located in Oakland, in Alameda County, including Union Pacific, Southern Pacific, and Santa Fe railroads. From Oakland, there are two primary routes east:

Formed in 1909, the Oakland Antioch Railway was renamed the Oakland Antioch & Eastern Railway in 1911. It extended through a 3,400-foot (1,000 m) tunnel in the Oakland Hills, from Oakland to Walnut Creek, Concord and on to Bay Point.

The current owner of the Santa Fe Railroad's assets, BNSF Railway, has the terminus of its transcontinental route in Richmond. Originally built by the San Francisco and San Joaquin Valley Railroad in 1896, the line was purchased by the Atchison, Topeka and Santa Fe Railway shortly thereafter. The line leaves Richmond through industrial and residential parts of West County before striking due east through Franklin Canyon and Martinez on its way to Stockton, Bakersfield, and Barstow.

These railroads spurred the development of industry in the county throughout the late 19th and early 20th centuries, particularly driving development of the Standard Oil (now Chevron) refinery and port complex in Richmond.

There were a large number of short lines in the county between the late 19th century and the early 20th century. The rights of way of a number of these railroads also served as utility rights of way, particularly for water service, and so were preserved and in the late 20th century enhanced as walking, jogging, and bicycle riding trails in the central portion of the county.


Parks and recreation



California casino proposals

Since 2003, four Indian gaming casinos have been proposed in Richmond and the surrounding area of West Contra Costa County.



Martinez Court House Contra Costa County Hall of Records (Martinez, CA).jpg
Martinez Court House



Census-designated places

Unincorporated communities

Former communities

Ohmer was a rail station located on the Oakland, Antioch and Eastern Railroad 6 miles (9.7 km) east of Martinez, which still appeared on maps as of 1947. Though primarily just a rail station, it was sometimes referred to as a community. [75]

Ghost towns

Other places

Population ranking

The population ranking of the following table is based on the 2020 census of Contra Costa County. [76]

county seat

RankCity/Town/etc.Municipal typePopulation (2020 Census)
1 Concord City125,410
2 Richmond City116,448
3 Antioch City115,291
4 San Ramon City84,605
5 Pittsburg City76,416
6 Walnut Creek City70,127
7 Brentwood City64,292
8 Danville Town43,582
9 Oakley City43,357
10 Martinez City37,287
11 Pleasant Hill City34,613
12 San Pablo City32,127
13 Hercules City26,016
14 El Cerrito City25,962
15 Lafayette City25,391
16 Bay Point CDP23,896
17 Orinda City19,514
18 Pinole City19,022
19 Moraga Town16,870
20 El Sobrante CDP15,524
21 Discovery Bay CDP15,358
22 Alamo CDP15,314
23 Clayton City11,070
24 Rodeo CDP9,653
25 Blackhawk CDP9,637
26 Contra Costa Centre CDP6,808
27 Saranap CDP5,830
28 Kensington CDP5,428
29 Tara Hills CDP5,364
30 Camino Tassajara CDP4,951
31 Vine Hill CDP4,323
32 Pacheco CDP4,183
33 North Richmond CDP4,175
34 San Miguel CDP3,591
35 East Richmond Heights CDP3,460
36 Reliez Valley CDP3,354
37 Crockett CDP3,242
38 Montalvin Manor CDP3,099
39 Rollingwood CDP3,015
40 Mountain View CDP2,622
41 Bethel Island CDP2,131
42 Bayview CDP1,782
43 Knightsen CDP1,596
44 Castle Hill CDP1,271
45 Diablo CDP1,255
46 Byron CDP1,140
47 Acalanes Ridge CDP1,285
48 Shell Ridge CDP1,014
49 Norris Canyon CDP1,313
50 Alhambra Valley CDP805
51 North Gate CDP667
52 Clyde CDP729
53 Port Costa CDP190

See also


  1. For a collection of observations of the Mexican provincial culture and trading practice (most notably in the acquisition of cattle hides for eastern U.S. shoe manufacturies) see portions of Two Years Before the Mast , a first-person narrative of a seaman's voyage to California starting in 1834.
  2. Other = Some other race + Two or more races
  3. Native American = Native Hawaiian or other Pacific Islander + American Indian or Alaska Native
  4. 1 2 Percentage of registered voters with respect to total population. Percentages of party members with respect to registered voters follow.

Related Research Articles

<span class="mw-page-title-main">Alamo, California</span> Unincorporated community in California, United States

Alamo is an unincorporated community and census-designated place (CDP) in Contra Costa County, California, in the United States. It is a suburb located in the San Francisco Bay Area's East Bay region, approximately 28 miles (45 km) east of San Francisco. Alamo is equidistant from the city of Walnut Creek and the incorporated town of Danville. As of the 2020 census, the population was 15,314.

<span class="mw-page-title-main">Brentwood, California</span> City in California, United States

Brentwood, or “Corn Town”, is a city in Contra Costa County, California, United States. It is located in the East Bay region of the San Francisco Bay Area. The population is 66,854 as of 2022, an increase of 287% from 23,302 at the 2000 census.

<span class="mw-page-title-main">Concord, California</span> City in California, United States

Concord is the most populous city in Contra Costa County, California, United States. According to an estimate completed by the United States Census Bureau, the city had a population of 129,295 in 2019, making it the eighth largest city in the San Francisco Bay Area. Founded in 1869 as Todos Santos by don Salvio Pacheco II, a noted Californio ranchero, the name was later changed to Concord. The city is a major regional suburban East Bay center within the San Francisco Bay Area, and is 29 miles east of San Francisco.

<span class="mw-page-title-main">Martinez, California</span> City in California, United States

Martinez is a city and the county seat of Contra Costa County, California, United States, in the East Bay region of the San Francisco Bay Area. Located on the southern shore of the Carquinez Strait, the city's population was 37,287 at the 2020 census. The city is named after Californio ranchero Ygnacio Martínez, having been founded on his Rancho El Pinole. Martinez is known for its historic center and its waterfront.

<span class="mw-page-title-main">Pacheco, California</span> Census-designated place in California, United States

Pacheco is a census-designated place (CDP) in Contra Costa County, California. The population was 3,685 at the 2010 census. It is bounded by Martinez to the north and west, Concord to the east, and Pleasant Hill to the south.

<span class="mw-page-title-main">Walnut Creek, California</span> City in California, United States

Walnut Creek is a city in Contra Costa County, California, United States, located in the East Bay region of the San Francisco Bay Area, about 16 miles east of the city of Oakland. Walnut Creek has a total population of 70,127 per the 2020 census, is located at the junction of the highways from Sacramento and San Jose (I-680) and San Francisco/Oakland (SR-24), and is accessible by BART. The city shares its borders with Clayton, Lafayette, Alamo, Pleasant Hill, and Concord.

<span class="mw-page-title-main">County Connection</span> Public transit agency in Contra Costa County, California

The County Connection is a Concord-based public transit agency operating fixed-route bus and ADA paratransit service in and around central Contra Costa County in the San Francisco Bay Area. Established in 1980 as a joint powers authority, CCCTA assumed control of public bus service within central Contra Costa first begun by Oakland-based AC Transit as it expanded into suburban Contra Costa County in the mid-1970s. In 2022, the system had a ridership of 2,226,500, or about 9,400 per weekday as of the third quarter of 2023.

<span class="mw-page-title-main">East Bay</span> Eastern region of the San Francisco Bay Area, California, US

The East Bay is the eastern region of the San Francisco Bay Area and includes cities along the eastern shores of the San Francisco Bay and San Pablo Bay. The region has grown to include inland communities in Alameda and Contra Costa counties. With a population of roughly 2.5 million in 2010, it is the most populous subregion in the Bay Area.

The San Ramon Valley is a valley and region in Contra Costa County and Alameda County, in the East Bay region of the San Francisco Bay Area in northern California.

<i>East Bay Times</i> California newspaper

The East Bay Times is a daily broadsheet newspaper based in Walnut Creek, California, United States, owned by the Bay Area News Group (BANG), a subsidiary of Media News Group, that serves Contra Costa and Alameda counties, in the East Bay region of the San Francisco Bay Area. It was founded as the Contra Costa Times, and took its current name in 2016 when it was merged with other sister papers in the East Bay. Its oldest merged title is the Oakland Tribune founded in 1874.

California's 10th congressional district is a congressional district in the U.S. state of California. Currently, the 10th district encompasses parts of the eastern San Francisco Bay Area. It is currently represented by Democrat Mark DeSaulnier.

Morgan Territory is an historic ranching area on the east side of Mount Diablo in San Francisco East Bay's Contra Costa County. It was named after Anglo-American pioneer Jeremiah Morgan, a migrant from Alabama and Iowa who acquired 2000 acres and developed a ranch here, starting in 1857.

John Muir Health is a hospital network headquartered in Walnut Creek, California and serving Contra Costa County, California and surrounding communities. It was formed in 1997 from the merger of John Muir Medical Center and Mount Diablo Medical Center.

Mount Diablo Unified School District (MDUSD) is a public school district in Contra Costa County, California. It currently operates 29 elementary schools, 9 middle schools, and 5 high schools, with 7 alternative school programs and an adult education program. MDUSD is one of the largest school districts in the state of California, with over 56 school sites and a budget of approximately $270,000,000. The district has over 36,000 K-12 students, over 20,000 adult education students, and over 3,500 employees, including over 2,000 certificated educators. The district covers 150 square miles (390 km2), including the cities of Concord and Clayton; as well as most of Pleasant Hill and portions of Walnut Creek, Pittsburg, Lafayette, and Martinez; and unincorporated areas, including Pacheco, Clyde, and Bay Point.

<span class="mw-page-title-main">John A. Nejedly</span> American politician

John Albert Nejedly was a district attorney and Republican state senator in California who represented Contra Costa County from 1958 to 1980.

<span class="mw-page-title-main">Briones Regional Park</span>

Briones Regional Park is a 6,117-acre (24.75 km2) regional park in the East Bay Regional Park District (EBRPD) system, located in the Briones Hills of central Contra Costa County of the San Francisco Bay Area in California.

The Contra Costa County Board of Supervisors is the governing body for Contra Costa County, California, in the San Francisco Bay Area's East Bay region. Members of the Board of supervisors are elected from districts, based on their residence.

Rancho Las Juntas was a 13,293-acre (53.79 km2) Mexican land grant in present day Contra Costa County, California given in 1844 by Governor Manuel Micheltorena to William Welch. The name Las Juntas translates as "the Crossroads". The grant was located between Ygnacio Martinez’ Rancho El Pinole and Salvio Pacheco’s Rancho Monte del Diablo, and included northwestern Walnut Creek, all of Pleasant Hill, and the eastern portion of Martinez. The original borders of the claim were defined as the straits to the north, "Las Juntas" to the south, the Walnut creek to the east, the Reliz ridge to the west, and, to the northwest, the Alhambra creek.

<span class="mw-page-title-main">Walnut Creek (California)</span> Stream in Contra Costa County

The Walnut Creek mainstem is a 12.3-mile-long (19.8-kilometer) northward-flowing stream in northern California. The Walnut Creek watershed lies in central Contra Costa County, California and drains the west side of Mount Diablo and the east side of the East Bay Hills. The Walnut Creek mainstem is now mostly a concrete or earthen flood control channel until it reaches Pacheco Creek on its way to Suisun Bay. Walnut Creek was named for the abundant native Northern California walnut trees which lined its banks historically. The city of Walnut Creek, California was named for the creek when its post office was established in the 1860s.

<span class="mw-page-title-main">Las Trampas Ridge</span>

Las Trampas Ridge is an 1,827 ft ridge in western Contra Costa County, California, in the San Francisco Bay Area. It comprises the western side of the San Ramon Valley.


  1. "Chronology". California State Association of Counties. Archived from the original on January 29, 2016. Retrieved February 6, 2015.
  2. "District Offices | Contra Costa County, CA Official Website".
  3. "County Administrator's Office | Contra Costa County, CA Official Website".
  4. "Mount Diablo". Archived from the original on May 2, 2015. Retrieved February 6, 2015.
  5. "Gross Domestic Product by County and Metropolitan Area, 2022" (PDF). Bureau of Economic Analysis.
  6. "Contra Costa County, California". United States Census Bureau . Retrieved January 30, 2022.
  7. "Contra Costa County, California Official Website". Archived from the original on June 18, 2018. Retrieved January 24, 2009.
  8. "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved 2011-06-07.
  9. "Contra Costa County, California Official Website - Visiting". Archived from the original on February 27, 2009. Retrieved 2009-01-24.
  10. "Contra Costa County Mexican Land Grants". June 16, 2003. Archived from the original on November 24, 2009. Retrieved September 22, 2012.
  11. U.S. 1850 California Census asks state of birth of all residents and gets about 7300 residents born in California. Adding the approximate 200 Hispanics known to be in San Francisco (1846 directory) and an unknown (but small as shown in 1852 CA Census recount) number in Contra Costa and Santa Clara county whose census was lost gives less than 9,000 Hispanics state wide.
  12. Lyman, George D. John Marsh, Pioneer: The Life Story of a Trail-blazer on Six Frontiers, pp. 237–49, The Chautauqua Press, Chautauqua, New York, 1931.
  13. U.S. 1850 California Census counts 92,597 residents but omits the residents of San Francisco (estimated at 21,000) whose census records were destroyed by fire. Contra Costa County (estimated at 2,000 residents) and Santa Clara County (estimated at 4,000 residents) 1850 records were "lost" and also not included.
  14. Historical Statistics of the United States--1850-California,, which includes a summary of the state's 1852 state census
  15. "Population of the United States in 1860: California", United States census,1860; page 22,. Retrieved on 17 June 2021.
  16. "Point Pinole". Archived from the original on June 9, 2007.
  17. "East Bay Regional Parks | Embrace Life!". Archived from the original on October 19, 2004. Retrieved September 22, 2012.
  18. "2010 Census Gazetteer Files". United States Census Bureau. August 22, 2012. Archived from the original on September 25, 2015. Retrieved September 24, 2015.
  19. "Planning Framework". Contra Costa County. July 2010. Retrieved April 22, 2019.
  20. "Census of Population and Housing from 1790-2000". US Census Bureau . Retrieved January 24, 2022.
  21. "Historical Census Browser". University of Virginia Library. Archived from the original on August 11, 2012. Retrieved September 24, 2015.
  22. Forstall, Richard L., ed. (March 27, 1995). "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Archived from the original on September 24, 2015. Retrieved September 24, 2015.
  23. "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. April 2, 2001. Archived (PDF) from the original on December 18, 2014. Retrieved September 24, 2015.
  24. 1 2 "P2 HISPANIC OR LATINO, AND NOT HISPANIC OR LATINO BY RACE - 2010: DEC Redistricting Data (PL 94-171) - Contra Costa County, California". United States Census Bureau .
  25. 1 2 "P2 HISPANIC OR LATINO, AND NOT HISPANIC OR LATINO BY RACE - 2020: DEC Redistricting Data (PL 94-171) - Contra Costa County, California". United States Census Bureau .
  26. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates, Table B02001. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-26.
  27. 1 2 U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates, Table B03003. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-26.
  28. 1 2 U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates, Table B19301. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-21.
  29. 1 2 U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates, Table B19013. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-21.
  30. 1 2 U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates, Table B19113. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-21.
  31. 1 2 U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-21.
  32. U.S. Census Bureau. American Community Survey, 2011 American Community Survey 5-Year Estimates, Table B01003. U.S. Census website Archived December 27, 1996, at the Wayback Machine . Retrieved 2013-10-21.
  33. "2010 Census P.L. 94-171 Summary File Data". United States Census Bureau.
  34. "Demographic Profile Bay Area Census". Archived from the original on December 27, 1996.
  35. "U.S. Census website". United States Census Bureau. Archived from the original on December 27, 1996. Retrieved 2011-05-14.
  36. "Contra Costa County, California - Fact Sheet - American FactFinder". Archived from the original on February 10, 2020. Retrieved September 22, 2012.
  37. "County Membership Reports". Archived from the original on May 11, 2011. Retrieved August 22, 2011.
  38. "County Membership Reports". Archived from the original on May 11, 2011. Retrieved August 22, 2010.
  39. Berkowitz, Dovber (October 21, 2015). "Where Does the Soul Go After It Departs This World?".
  40. Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". Archived from the original on November 17, 2013. Retrieved August 31, 2018.
  41. "Counties by County and by District". California Citizens Redistricting Commission. Archived from the original on September 30, 2013. Retrieved September 24, 2014.
  42. 1 2 3 4 5 6 7 8 9 10 11 12 "Statement of Vote, November 8, 2022, General Election" (PDF). California Secretary of State. Retrieved May 5, 2023.
  43. 1 2 3 4 5 6 Contra Costa County Elections Division. Archived November 30, 2016, at the Wayback Machine . Retrieved 2016-11-29.
  44. 1 2 3 4 5 6 7 8 9 10 "Table 11: Crimes 2009" (PDF). Office of the Attorney General, Department of Justice, State of California. Archived from the original (PDF) on December 2, 2013. Retrieved November 14, 2013.
  45. Only larceny-theft cases involving property over $400 in value are reported as property crimes.
  46. 1 2 3 United States Department of Justice, Federal Bureau of Investigation. Crime in the United States, 2019, Table 8 (California) Archived October 19, 2020, at the Wayback Machine . Retrieved 2021-1-3.
  47. "Highway 4 commute pegged as one of nation's worst". May 23, 2012.
  48. "Long-sought highway would connect East Contra Costa to the south". January 19, 2022.
  49. "CBS News article". January 31, 2011. Retrieved March 2, 2011.
  50. "CCTimes article". February 5, 2012. Archived from the original on September 4, 2015. Retrieved February 5, 2012.
  51. David Banister (December 16, 2003). Transport and Urban Development. Routledge. p. 145. ISBN   978-1-135-81992-7. Archived from the original on July 28, 2020. Retrieved August 29, 2019.
  52. "Concord Community Reuse Project | About". Archived from the original on February 13, 2017. Retrieved November 30, 2016.
  53. Hall, Carl (August 25, 2005) "East Bay Newspaper Chain Sold" Archived April 6, 2012, at the Wayback Machine , S.F. Chronicle. Retrieved 2007-08-16.
  54. "San Francisco counties to order three-week 'shelter in place' - San Francisco Chronicle". Reuters. March 16, 2020. Retrieved March 16, 2020.
  55. "". November 17, 2012. Archived from the original on September 28, 2007. Retrieved November 22, 2012.
  56. "The John Marsh House". Archived from the original on October 18, 2005.
  57. chinn, harvey. "The Martinez Adobe - John Muir National Historic Site - John Muir Exhibit (John Muir Education Project, Sierra Club California)". Archived from the original on June 2, 2014. Retrieved June 1, 2014.
  58. "Museum of the San Ramon Valley". Archived from the original on August 8, 2019. Retrieved November 22, 2012.
  59. "" Welcome to City of WALNUT CREEK California "". Archived from the original on June 6, 2008.
  60. "Briones Regional Park". Archived from the original on October 11, 2004. Retrieved September 22, 2012.
  61. "Diablo Foothills Regional Park". September 27, 2012. Archived from the original on November 12, 2012. Retrieved November 22, 2012.
  62. "Howe Homestead Park". Archived from the original on March 12, 2005.
  63. "Las Trampas Regional Wilderness". Archived from the original on November 12, 2012. Retrieved November 22, 2012.
  64. "Shell Ridge Open Space". Archived from the original on December 3, 2005.
  65. "Lime Ridge Open Space". Archived from the original on September 27, 2005.
  66. "San Pablo Recreation Area". Archived from the original on January 4, 2006.
  67. "Sugarloaf Open Space Recreation Area". Archived from the original on August 18, 2005.
  68. "Acalanes Ridge Open Space". Archived from the original on December 11, 2005.
  69. "Iron Horse Regional Trail". October 17, 2012. Archived from the original on November 12, 2012. Retrieved November 22, 2012.
  70. "California Riding and Hiking Trail". Archived from the original on March 21, 2018. Retrieved November 22, 2012.
  71. "Contra Costa Canal Trail". September 13, 2012. Archived from the original on November 22, 2012. Retrieved November 22, 2012.
  72. "Delta de Anza Regional Trail". Archived from the original on November 12, 2012. Retrieved November 22, 2012.
  73. "Briones to Mt. Diablo Regional Trail". Archived from the original on November 12, 2012. Retrieved November 22, 2012.
  74. "Lafayette-Moraga Regional Trail". Archived from the original on December 8, 2012. Retrieved November 22, 2012.
  75. Purcell, Mae Fisher. History of Contra Costa County Archived July 28, 2020, at the Wayback Machine , p. 309 (1940)
  76. "2020 U.S. Census website". United States Census Bureau. Archived from the original on May 29, 2023. Retrieved 2023-07-02.

37°56′N121°57′W / 37.93°N 121.95°W / 37.93; -121.95

  1. Marin, Solano, Sonoma and Contra Costa Counties' borders come to a common point c. 6 miles into San Francisco Bay (coming from the north). Thus, Sonoma County is an adjacent county. Hittell, Theodore Henry (1876). The codes and statutes of the State of California. A. L. Bancroft. pp.  514, 515. Retrieved August 20, 2012.