Indianapolis ( IN-dee-ə-NAP-ə-lis), colloquially known as Indy, is the capital and most populous city of the U.S. state of Indiana and the seat of Marion County. Indianapolis is situated in the state's central till plain region along the west fork of the White River. The city's official slogan, "Crossroads of America", reflects its historic importance as a transportation hub and its relative proximity to other major North American markets. At the 2020 census, the balance population was 887,642. Indianapolis is the 16th-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 in the nation after Phoenix, Austin, and Columbus. The Indianapolis metropolitan area is the 34th-most populous metropolitan statistical area in the U.S., home to 2.1 million residents. With a population of more than 2.6 million, the combined statistical area ranks 27th. Indianapolis proper covers 368 square miles (950 km2), making it the 19th-most extensive city by land area in the country. Indigenous peoples inhabited the area dating to as early as 10,000 BC. In 1818, the Lenape relinquished their tribal lands in the Treaty of St. Mary's. In 1821, Indianapolis was established as a planned city for the new seat of Indiana's state government. The city was platted by Alexander Ralston and Elias Pym Fordham on a 1-square-mile (2.6 km2) grid. Completion of the National and Michigan roads and later arrival of rail solidified the city's position as a major manufacturing and commercial center. Since the 1970 city-county consolidation, known as Unigov, local government administration operates under the direction of an elected 25-member city-county council headed by the mayor. Indianapolis anchors the 29th largest metropolitan economy in the U.S. Prominent industries include trade, transportation, and utilities; education and health services; professional and business services; government; leisure and hospitality; and manufacturing. The city has notable niche markets in amateur sports and auto racing. Contemporary Indianapolis is home to two major league sports teams, three Fortune 500 companies, eight university campuses, and numerous cultural institutions, including the world's largest children's museum. The city is perhaps best known for hosting the world's largest single-day sporting event, the Indianapolis 500. Among the city's historic sites and districts, Indianapolis is home to the largest collection of monuments dedicated to veterans and war casualties in the U.S. outside of Washington, D.C.