Charles Street, known for most of its route as Maryland Route 139, runs through Baltimore and the Towson area of Baltimore County. On the north end, it terminates at an intersection with Bellona Avenue near Interstate 695 (I-695). At the south end, it terminates in Federal Hill in Baltimore. Charles Street is one of the major routes through Baltimore, and is a major public transportation corridor. For the one-way portions of Charles Street, the street is functionally complemented by the parallel St. Paul Street, including St. Paul Place and Preston Gardens, Maryland Avenue, Cathedral Street, and Liberty Street.

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 city in the United States. Baltimore was designated an independent city by the Constitution of Maryland in 1851, and is currently the most populous independent city in the nation. As of the 2020 census, the population of the Baltimore metropolitan area was 2,838,327, the 20th-largest metropolitan area in the country. When combined with the larger Washington metropolitan area, the Washington–Baltimore combined statistical area (CSA) has a 2020 U.S. census population of 9,973,383, the third-largest in the country.