Maryland Route 22 (MD 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 (US 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.