Area codes 301 and 240
Area codes 301 and 240 are area codes that are part of Maryland. Area code 301 is one of the earliest area codes that were made in 1947. It initially covered the entire state until 1991, which is when it was split by 410, which covers the eastern part of the state, while 301 now covers the western portion of the state, including College Park, the Washington, St. Mary's, Prince George's, Allegany, Charles, Garrett, and Montgomery counties. It was overlaid by 240 in 1997.