Locations for Area Code - 301

Area code 301 serves western Maryland and the D.C. suburbs, including cities like Frederick, Hagerstown, and parts of Montgomery and Prince George’s Counties. Established in 1947, it is one of the original North American area codes. In 1997, it was overlaid with 240 to meet rising demand, making ten-digit dialing necessary. This region hosts a mix of urban and rural areas, with strong ties to federal agencies, research institutions, and suburban communities. Area code 301 reflects Maryland’s historical depth and geographic diversity, playing a key role in the broader D.C. metro region’s identity and infrastructure.