Contra Costa County 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. The county seat is Martinez. 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. Contra Costa County is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area.
Clayton is a city in Contra Costa County, California, United States. The population was 11,585 as of the 2020 census.
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.
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.
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.
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.
John Marsh, later known in Spanish as Don Juan Marsh, was a physician, ranchero, and linguist in California when it was still part of the Republic of Mexico. Born in Massachusetts, Marsh immigrated to California in 1836, where he became a Mexican citizen. He was baptized as Roman Catholic in order to buy land, and acquired the vast land grant of Rancho Los Méganos in Contra Costa. He became one of the wealthiest ranchers in California, and was among the highly influential men who worked to gain United States statehood after Mexico ceded this area following its defeat in the Mexican-American War.
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.
Pacheco Creek is a 3.4-mile-long (5.5 km) waterway in central Contra Costa County, California, United States. It empties into Suisun Bay. It is formed by the intersection of Walnut Creek, Grayson Creek and Pine Creek.
Rancho Arroyo de Las Nueces y Bolbones was a 17,782-acre (71.96 km2) Mexican land grant in present-day Contra Costa County, California given in 1834 by Governor José Figueroa to Juana Sanchez de Pacheco.
Rancho San Ramon was a 8,917-acre (36.09 km2) Mexican land grant in the northern San Ramon Valley of present-day Contra Costa County, California. Rancho San Ramon (Amador) was adjacent in the southern San Ramon Valley.
Rancho Monte del Diablo was a 17,921-acre (72.52 km2) Mexican land grant in present-day Contra Costa County, California given in 1834 by Governor José Figueroa to Salvio Pacheco. The name "Monte del Diablo" means "thicket of the devil" in Spanish. The name was later incorrectly translated as Mount Diablo. The grant covered the area from the Walnut Creek channel east to the hills, and generally from the Mount Diablo foothills north along Lime Ridge to Avon on the Carquinez Strait of the Sacramento River, and included present day Concord and parts of Pleasant Hill. Pacheco and Clayton are outside of the Rancho Monte del Diablo grant.
Rancho San Jose was a 6,659-acre (26.95 km2) Mexican land grant in present-day Marin County, California given in 1840 by Governor Juan Alvarado to Ygnacio Pacheco. The grant included the lands of Hamilton Air Force Base and the community of Ignacio.
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.
The Salvio Pacheco Adobe is a historic adobe house in Concord, California. It was built in 1835 by Salvio Pacheco, a Californio ranchero with vast lands in Contra Costa.
The Don Fernando Pacheco Adobe is located at 3119 Grant Street in Concord, California.The Fernando Pacheco Adobe is the only Concord landmark listed in all three Historical Registries: entry on the National Register occurred on June 6, 1980; the California Registered landmark number is 455; and the Concord Historical Landmark designation is 1-26-26/5458. The Adobe was built by Don Fernando in the early 1850s as the base of operations for his growing ranch activities, and as his family's formal residence. Fernando was the oldest son of Don Salvio Pacheco. He was born on May 30, 1818, while his father was assigned to a Militia-Guard unit at the Pueblo of San Jose. At age 17, he was sent to take possession and mark the boundaries of his father's 17,921 acre land grant. Fernando was given 1,500 acres as initial share of the rancho. He subsequently married Pasquala (Figeroa) (Juarez) – a widow. Their six children: Pedro, Bonifacio, Cipriana, Maria Asuncion, Librada and Bersabe were raised at the Adobe. Don Fernando's family enjoyed a reputation as gracious hosts. They were famous for their generosity and extensive fiestas on Adobe's then lush, well irrigated grounds. The Adobe's 32” thick walls were built of local adobe – mud.
The Moraga Adobe is located at 24 Adobe Lane in Orinda, California. It was built by Don Joaquin Moraga who was the grandson of Jose Joaquin Moraga an early Spanish explorer in California who founded the city of San Jose, California. In 1835, Mexico granted 13,326 acres (5,393 ha), El Rancho Laguna de los Palos Colorados, to Joaquin Moraga and his cousin Juan Bernal. Six years later in 1841, Joaquin built this house, which is the oldest of the five surviving adobe houses in Contra Costa County. The adobe sits on a knoll at the center of the 20-acre (8.1 ha) property of what is left of the original land grant. The house has been restored and remodeled twice since it was photographed for HABS, first in 1941 when Katharine Brown White Irvine of Oakland, California purchased the old adobe, making additions such as adding three bedrooms and a veranda, and covering the adobe walls and again in 1964 when it was incorporated into a private home. The house is not accessible to the public and it is fenced off. However, it was photographed in 1922 for the Historical American Building Survey (HABS). Today, the Moraga Adobe is privately owned and unoccupied. The overall condition of the original adobe section and the more modern addition is neglected, but the building appears sound. The surrounding property was recently purchased, and the new owners have boarded up the windows to prevent vandalism and trespassing. The Moraga Adobe has been designated as a Historical Landmark by the City of Orinda and the State of California. A campaign has been started to purchase the property and restore the house to its 1848 configuration, to be used as a museum and educational site.
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.
Don Juan Salvio Pacheco II (1793-1876) was a Californio ranchero and soldier. He founded the city of Concord, then known as Todos Santos. Pacheco also served three terms as Alcalde of San José.
