Maryland Route 22 is a state highway in the U.S. state of Maryland. The state highway runs 12.91 miles (20.78 km) from U.S. Route 1 Business and MD 924 in Bel Air east to an entrance to Aberdeen Proving Ground in Aberdeen. MD 22 is the main connection between the county seat of Bel Air and Aberdeen, which is the largest city in Harford County. The state highway also provides the primary route between Interstate 95 (I-95) and Aberdeen Proving Ground.

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.