U.S. Route 1 is a major north–south U.S. Highway that serves the East Coast of the United States. It runs 2,369 miles (3,813 km), from Fort Kent, Maine, at the Canadian border, south to Key West, Florida. US 1 is generally paralleled by Interstate 95, though the former 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, Washington, D.C., Philadelphia, New York City, and Boston passing from the Southeastern United States to New England.

While US 1 is generally the easternmost of the main north–south U.S. Highways, part of Routes 9, 13, 17, and 301 occupy corridors closer to the ocean. When the road 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 farther east were of lower quality and did not serve the major population centers.