Indianapolis (Wikipedia) Indianapolis (/ˌɪndiəˈnæpəlɪs/ IN-dee-ə-NAP-əl-iss), colloquially known as Indy, is the capital and most populous city of the U.S. state of Indiana and the seat of Marion County. According to the U.S. Census Bureau, the consolidated population of Indianapolis and Marion County was 977,203 in 2020. The “balance” population, which excludes semi-autonomous municipalities in Marion County, was 887,642. It is the 15th most populous city in the U.S., the third-most populous city in the Midwest, after Chicago and Columbus, Ohio, and the fourth-most populous state capital after Phoenix, Arizona, Austin, Texas, and Columbus. The Indianapolis metropolitan area is the 33rd most populous metropolitan statistical area in the U.S., with 2,111,040 residents. Its combined statistical area ranks 28th, with a population of 2,431,361. Indianapolis covers 368 square miles (950 km2), making it the 18th largest city by land area in the U.S.