North American area codes 240 and 301 are State of Maryland telephone area codes which serve Maryland's portion of the Greater Washington, D.C. metro area, portions of southern Maryland, and all points northwest of Washington. This includes the communities of Cumberland, Frederick, Hagerstown, and Gaithersburg. Area code 301 was one of the original area codes established in 1947, and was the exclusive area code for Maryland until it was split to form 410 on October 6, 1991. The overlay area code 240, was introduced on June 1, 1997.
Counties served by these area codes include:
Local calls require 10-digit dialing (area code + number, leading "1" is not required).
Area code 227 is scheduled to be overlaid with 301/240 some time in the longer term to provide additional assignable numbers, although the current area codes are not expected to exhaust before 2020.
| Maryland area codes: 240, 301, 410, 443 | ||
|---|---|---|
| North: 717, 724/878, 814 | ||
| West: 202, 304/681, 540, 571/703 | area codes 301/240 | East: 410/443 |
| South: 804, 304/681 | ||
| District of Columbia area codes: 202 | ||
| Pennsylvania area codes: 215, 267, 412, 484, 570, 610, 717, 724, 814, 878 | ||
| Virginia area codes: 276, 434, 540, 571, 703, 757, 804 | ||
| West Virginia area codes: 304, 681 | ||