Area Code 240

Area Code 240 History:

06/01/1997
Area code 240 was officially put into service. Area code 240 is an overlay of area code 301.

Area code 227 was put into service as a distributed overlay of area codes 240 and 301 in Maryland on 06/14/23. Ten digit dialing (area code + seven digit number) is necessary in the 227/240/301 overlay because different homes in the same geographic area can have the same seven digit phone number but each would have a different area code.

Counties in Maryland within area code 240 include:

Allegany County, Anne Arundel County, Calvert County, Charles County, Frederick County, Garrett County, Howard County, Montgomery County, Prince Georges County, Saint Marys County, and Washington County.

Major cities or places in Maryland within area code 240 include:

Area codes 227, 240 and 301 serve central and western Maryland including Bethesda, College Park, Frederick, Gaithersburg, Hagerstown, Landover, Rockville, Silver Springs and Weaton-Glenmont in addition to many smaller communities northwest of Washington, D.C.