Area code 301 serves western and southern Maryland, including cities such as Frederick, Hagerstown, Waldorf, and parts of the Washington, D.C. suburbs. It is one of the original area codes created in 1947 and originally served the entire state. In 1991, the eastern portion of the state was split off to form 410, and in 1997, overlay 240 was introduced to cover the 301 region. The area includes both rural landscapes and fast-growing suburban corridors. With proximity to Washington, D.C., 301 is associated with federal agencies, defense contractors, and commuters. It remains a widely recognized and historically significant area code in Maryland.