U.S. Route 1 (US 1) is a major north-south U.S. Highway that serves the East Coast of the United States. It runs over 2000 miles (3000 km) from Key West, Florida north to Fort Kent, Maine at the Canadian border. US 1 generally parallels Interstate 95, though it is significantly farther west (inland) between Jacksonville, Florida and Petersburg, Virginia. The highway connects most of the major cities of the east coast, including Miami, Florida; Jacksonville, Florida; Augusta, Georgia; Columbia, South Carolina; Raleigh, North Carolina; Richmond, Virginia; Washington, D.C.; Baltimore, Maryland; Philadelphia, Pennsylvania; Newark, New Jersey; New York, New York; New Haven, Connecticut; Providence, Rhode Island; Boston, Massachusetts; and Portland, Maine.

US 1 is the easternmost of the main north-south U.S. Highways, all of which end in one, but in areas it is not the easternmost route of the system, with large portions of US 9, US 13, and US 17 occupying corridors closer to the ocean. When the system was laid out in the 1920s, US 1 was mostly assigned to the existing Atlantic Highway, which followed the fall line between the Piedmont and the Atlantic Coastal Plain north of Augusta, Georgia. At the time, the highways further east were of lower quality and did not serve the major population centers. Rand McNally Auto Road Atlas, 1926, accessed via the Broer Map Library