The low rolling hills of Marion County have been cleared of trees, and the area is completely devoted to municipal development or to agriculture, except for wooded drainages.[3] The highest point (920 feet/280 meters ASL) is a small ridge at the county's northwest corner.[4]
According to the 2010 census, the county has an area of 403.01 square miles (1,043.8km2), of which 396.30 square miles (1,026.4km2) (or 98.34%) is land and 6.71 square miles (17.4km2) (or 1.66%) is water.[5]
The White River flows southwestward through the central part of the county; it is joined by Eagle Creek and Fall Creek, both of which have dams in the county forming Eagle Creek Reservoir and Geist Reservoir, respectively.
In recent years, average temperatures in Indianapolis have ranged from a low of 20°F (−7°C) in January to a high of 86°F (30°C) in July, although a record low of −22°F (−30°C) was recorded in January 1985 and a record high of 104°F (40°C) was recorded in June 1988. Average monthly precipitation ranged from 2.05 inches (52mm) in January to 4.78 inches (121mm) in July.[9]
US Decennial Census[11] 1790-1960[12] 1900–1990[13] 1990-2000[1]
Racial and ethnic composition
Marion County, Indiana – Racial and ethnic composition 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 may be of any race.
As of the 2020 census, the county had a population of 977,203. The median age was 34.7 years. 24.0% of residents were under the age of 18 and 12.9% of residents were 65 years of age or older. For every 100 females there were 94.0 males, and for every 100 females age 18 and over there were 90.9 males age 18 and over.[17][18]
99.1% of residents lived in urban areas, while 0.9% lived in rural areas.[19]
There were 398,062 households in the county, of which 30.0% had children under the age of 18 living in them. Of all households, 35.5% were married-couple households, 22.4% were households with a male householder and no spouse or partner present, and 33.3% were households with a female householder and no spouse or partner present. About 32.7% of all households were made up of individuals and 9.9% had someone living alone who was 65 years of age or older.[17]
There were 436,998 housing units, of which 8.9% were vacant. Among occupied housing units, 52.9% were owner-occupied and 47.1% were renter-occupied. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 10.3%.[17]
2010 census
As of the 2010 U.S. census, there were 903,393 people, 366,176 households, and 218,338 families in the county.[20] The population density was 2,279.6 inhabitants per square mile (880.2/km2). There were 417,862 housing units at an average density of 1,054.4 per square mile (407.1/km2).[5] The racial makeup of the county was 62.7% white, 26.7% black or African American, 2.0% Asian, 0.3% American Indian, 0.1% Pacific islander, 5.4% from other races, and 2.8% from two or more races. Those of Hispanic or Latino origin made up 9.3% of the population.[20] In terms of ancestry, 18.9% were German, 11.8% were Irish, 8.4% were English, 6.6% were American, and 5.2% were Subsaharan African.[21]
Of the 366,176 households, 32.3% had children under the age of 18 living with them, 36.9% were married couples living together, 17.1% had a female householder with no husband present, 40.4% were non-families, and 32.0% of all households were made up of individuals. The average household size was 2.42 and the average family size was 3.08. The median age was 33.9 years.[20]
The median income for a household in the county was $47,697 and the median income for a family was $54,142. Males had a median income of $42,215 versus $34,169 for females. The per capita income for the county was $24,498. About 13.5% of families and 17.3% of the population were below the poverty line, including 25.7% of those under age 18 and 9.0% of those age 65 or over.[22]
Cities and towns
Marion County has a consolidated city-county government, known as Unigov, in which only four municipalities retain full government autonomy (including a mayor and city council) as "excluded cities". The remaining municipalities within the county are "included towns" and exercise very limited authority, mainly in zoning and appointing their own police departments and maintaining some of their own municipal services and town identities. They retain the ability to levy taxes for these purposes.
Marion County has nine townships roughly organized into a grid-like, three-by-three pattern. This arrangement can be seen below, with the top being north.
The northern two-thirds of Marion County is in Indiana's 7th congressional district, which is held by Democrat André Carson. Indiana's 6th congressional district, which runs along the southern third of the county, is held by Republican Jefferson Shreve. The county is represented by 15 seats in the Indiana House of Representatives, 86th through 100th districts, with ten seats held by Democrats and five by Republicans. In the State Senate Marion County is divided among nine districts, which are held by two Democrats and seven Republicans. The Senate districts are numbered 28 through 36.
The Indianapolis City-County Council is the combined legislative body of Indianapolis and Marion County. The consolidated government, known as Unigov, was formally established in 1970 upon the merger of the city government with the county government. The council passes ordinances for the city and county, and makes appointments to certain boards and commissions.
The Auditor, Assessor, and Treasurer form the county's Board of Commissioners.
For most of the 20th century, Marion County was considered one of the most conservative urban counties in the nation. Between 1896 and 2000, it went Democratic only four times, in the national landslides of 1932, 1936 and 1964 as well as 1912 when Woodrow Wilson won a plurality in the county. The Republican edge narrowed considerably in the 1990s, and in 2004 John Kerry became the first Democrat since Lyndon B. Johnson in 1964 to carry the county. The trend continued in 2008 and 2012 with Barack Obama showing strongly in Marion County, winning 63% and 60% of the vote respectively. In the former case, Obama's showing in the county was enough to deliver Indiana to the Democrats for the first time since 1964, while John McCain became the first Republican since 1912 to win less than 40 percent of the county's vote. Hillary Clinton won it with 58 percent in 2016, and Joe Biden took 63 percent in 2020. Biden's 247,772 votes is the highest number of votes a candidate has ever received in the county. It is now one of the few Democratic bastions in traditionally heavily Republican central Indiana, and in the 2020 and 2024 elections, it was the most Democratic county in the entire state.[23]
The six northern and central townships lean more Democratic, especially Center Township containing Downtown Indianapolis, and Pike Township in the northwestern corner with an African-American majority. In contrast, the three less populated southern townships with a higher Caucasian population (Decatur, Perry and Franklin) lean more Republican.[24]
United States presidential election results for Marion County, Indiana[25]
↑Divita, James J. (1994). "Demography and Ethnicity". In Bodenhamer, David J.; Barrows, Robert G. (eds.). The Encyclopedia of Indianapolis. Bloomington and Indianapolis: Indiana University Press. pp.51–52. ISBN0-253-31222-1. Retrieved July 30, 2013.
↑Baker, Ronald L.; Marvin Carmony (1995). Indiana Place Names. Bloomington: Indiana University Press. p.98. ISBN0-253-28340-X.
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