Des Moines (/dəˈmɔɪn/) is the capital and the most populous city in the U.S. state of Iowa. It is also the county seat of Polk County. A small part of the city extends into Warren County. It was incorporated on September 22, 1851, as Fort Des Moines, which was shortened to "Des Moines" in 1857. It is located on, and named after, the Des Moines River, which likely was adapted from the early French name, Rivière des Moines, meaning "River of the Monks". The city's population was 214,133 as of the 2020 census. The six-county metropolitan area is ranked 83rd in terms of population in the United States with 699,292 residents according to the 2019 estimate by the United States Census Bureau, and is the largest metropolitan area fully located within the state.