Aspen Hill, Maryland

Where Is Area Code 301?

Area code 301 is in western and central Maryland. It serves Aspen Hill and much of Montgomery County, along with parts of Prince George's County, St. Mary's County, Charles County, Calvert County, Frederick County, Washington County, Allegany County, and Garrett County. It also covers cities and communities such as Rockville, Bethesda, Silver Spring, Gaithersburg, Hagerstown, Frederick, Waldorf, and Cumberland.

Area code 301 covers a wide stretch of Maryland from the Washington, D.C., suburbs to the state's western border. Aspen Hill is an unincorporated community in Montgomery County, north of Washington, D.C. The area includes suburban communities near the Capital Beltway and rural parts of western Maryland.

Area code 301 also reaches places with well-known federal and regional landmarks. These include the National Institutes of Health in Bethesda, the University of Maryland in College Park, and portions of the Chesapeake Bay region in southern Maryland. In western Maryland, the area includes mountain communities near the Appalachian Mountains.

History of Area Code 301

Area code 301 is one of the original North American area codes created in 1947. It originally covered the entire state of Maryland. As telephone use grew, Maryland's numbering system changed to handle more demand.

In 1991, area code 410 split from 301 and took much of eastern Maryland, including Baltimore. In 1997, area code 240 was added as an overlay for the 301 region. In 2023, area code 227 was added as a second overlay for the same geographic area. Because of these overlays, 10-digit dialing is required in the 301 area.

Key Facts About Area Code 301

• Area code 301 is in Maryland and serves Aspen Hill, Rockville, Bethesda, Silver Spring, Frederick, Hagerstown, Waldorf, and Cumberland.
• Area code 301 is in the Eastern Time Zone.
• Area code 301 is an original area code that began service in 1947.
• Area code 301 originally covered all of Maryland before later splits reduced its geographic reach.
• Area code 240 overlays the same region as area code 301, and area code 227 also overlays that region.
• Area code 301 serves parts of western Maryland, southern Maryland, and the Maryland suburbs of Washington, D.C.
• Area code 301 covers places that include the National Institutes of Health in Bethesda and the University of Maryland in College Park.
• Aspen Hill is a community in Montgomery County, Maryland, within the 301 and overlay service area.

Frequently Asked Questions

What state is area code 301 in?

Area code 301 is in Maryland.

What major cities use area code 301?

Major cities and communities in area code 301 include Rockville, Bethesda, Silver Spring, Gaithersburg, Frederick, Hagerstown, Waldorf, and Cumberland.

Is area code 301 a toll-free number?

No, area code 301 is a geographic area code.