Baltimore is an independent city and the largest city in the state of Maryland in the United States. Baltimore is located in central Maryland at the head of the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Founded in 1729, Baltimore is a major U.S. seaport and is situated closer to major Midwestern markets than any other major seaport on the East Coast. Baltimore's Inner Harbor was once the second leading port of entry for immigrants to the United States and a major manufacturing center. The harbor is now home to the Harborplace, a shopping and entertainment center, and the National Aquarium in Baltimore. After a decline in manufacturing industries, Baltimore shifted to a service sector-oriented economy. Johns Hopkins University and Johns Hopkins Hospital are now the city's largest employers.