The area code 301 is located in Aspen Hill, Maryland.
Area code 301 serves Aspen Hill, Maryland in Montgomery County and spans much of western and southern Maryland, including key suburbs of Washington, D.C. It was one of the original North American Numbering Plan codes created in 1947; after Maryland split with 410 in 1991, 301 stayed with the Washington metro side, then gained overlays 240 in 1997 and 227 in 2023, so 10-digit dialing is required. The 301/240/227 region includes major communities and landmarks such as the University of Maryland in College Park and NASA’s Goddard Space Flight Center in Greenbelt, along with hubs across Montgomery, Prince George’s, Frederick, Washington, Charles, St. Mary’s, Allegany, and Garrett counties. For Aspen Hill callers, a 301 phone number signals a local connection to nearby Rockville, Silver Spring, and Bethesda, making it a familiar choice for residents and businesses. The area uses Eastern Time, and many users keep their 301 numbers when moving within the region thanks to number portability.
Covered cities and landmarks include:
“Established in 1947, 301 originally served all of Maryland before later splits and overlays.” — North American Numbering Plan Administration (NANPA)