U.S. Route 1 Business is a business route of US 1 in the U.S. state of Maryland. The highway runs 6.90 miles (11.10 km) from US 1 and Maryland Route 147 (MD 147) in Benson north to US 1 near Hickory. US 1 Bus. is the old alignment of US 1 through Bel Air, the county seat of Harford County. US 1 was originally constructed on both sides of Bel Air in the early 1910s. The U.S. Route was widened in the 1920s, 1930s, and 1950s. US 1 Bus. was assigned to the highway from Benson through Bel Air to south of Hickory after the Bel Air Bypass was built in the mid-1960s. US 1 Bus. was extended north through Hickory when US 1 bypassed Hickory in 2000.

U.S. Route 1 (US 1) is the easternmost and longest of the major north–south routes of the older 1920s era United States Numbered Highway System, running from Key West, Florida, to Fort Kent, Maine. In the U.S. state of Maryland, it runs 81 miles (130 km) from the Washington, D.C. line to the Pennsylvania state line near the town of Rising Sun.