Some cities covered by area code 301 are Aspen Hill, Bowie, Chillum, Clinton, College Park, Cumberland, Fairland, Fort Washington, Frederick, Gaithersburg, Germantown, Greenbelt, Hagerstown, Landover, Montgomery Village, North Bethesda, North Potomac, Olney, Potomac, Rockville, Saint Charles, Silver Spring, South Laurel, Suitland, Waldorf, White Oak