Baltimore is the most populous city in the U.S. state of Maryland. With a population of 585,708 at the 2020 census, it is the 30th-most populous US city. Baltimore was designated an independent city by the Constitution of Maryland in 1851, and is the most populous independent city in the nation. As of 2020, the population of the Baltimore metropolitan area was 2,838,327, the 20th-largest metropolitan area in the country. When combined the Washington–Baltimore combined statistical area (CSA) had a 2020 population of 9,973,383, the third-largest in the country. Though the city is not located within or under the administrative jurisdiction of any county in the state, it is part of the Central Maryland region, together with the surrounding county that shares its name. The land that is present-day Baltimore was used as hunting ground by Paleo-Indians. In the early 1600s, the Susquehannock began to hunt there. People from the Province of Maryland established the Port of Baltimore in 1706 to support the tobacco trade with Europe, and established the Town of Baltimore in 1729. During the American Revolutionary War, the Second Continental Congress, fleeing Philadelphia prior to its fall to British troops, moved their deliberations to Henry Fite House on West Baltimore Street from December 1776, to February 1777, permitting Baltimore to serve briefly as the nation's capital, before it returned to Philadelphia in March 1777. The Battle of Baltimore was pivotal during the War of 1812, culminating in the failed British bombardment of Fort McHenry, during which Francis Scott Key wrote a poem that would become "The Star-Spangled Banner", designated as the national anthem in 1931. During the Pratt Street Riot of 1861, the city was the site of some of the earliest violence associated with the American Civil War. The Baltimore and Ohio Railroad, the nation's oldest, was built in 1830 and cemented Baltimore's status as a transportation hub, giving producers in the Midwest and Appalachia access to the city's port. Baltimore's Inner Harbor was the second leading port of entry for immigrants to the US and a major manufacturing center. After a decline in major manufacturing, heavy industry, and restructuring of the rail industry, Baltimore has shifted to a service-oriented economy. Johns Hopkins Hospital and University are the top employers. Baltimore is home to the Baltimore Orioles of Major League Baseball, and the Baltimore Ravens of the National Football League. Many Baltimore neighborhoods have rich histories. The city is home to some of the earliest National Register Historic Districts in the nation, including Fell's Point, Federal Hill, and Mount Vernon. Baltimore has more public statues and monuments per capita than any other city in the country. Nearly one third of the buildings (over 65,000) are designated as historic in the National Register, more than any other US city. Baltimore has 66 National Register Historic Districts and 33 local historic districts. The historical records of the government of Baltimore are located at the Baltimore City Archives.