Maryland Route 140 is a 49-mile (79 km) state highway in the U.S. state of Maryland. The route runs from U.S. Route 1 and US 40 Truck in Baltimore northwest to the Pennsylvania border, where the road continues into that state as Pennsylvania Route 16. MD 140 passes through the northern part of central Maryland, connecting Baltimore, Pikesville, Reisterstown, Westminster, Taneytown, and Emmitsburg.

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.