Locations for Area Code - 240

Area code 240 is an overlay of 301 and serves western Maryland, including cities like Frederick, Hagerstown, and parts of the Washington, D.C. suburbs such as Rockville and Silver Spring. Introduced in 1997, it reflects the region’s suburban and government-driven growth. Ten-digit dialing is required. Area code 240 supports a diverse population and strong links to federal employment, biotech industries, and the D.C. metro area, offering a modern counterpart to its historical predecessor, 301.