Area codes 240 and 301

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Area code 215Area code 856Area code 484Area code 717Area code 814Area code 724Area code 202Area code 571Area code 757Area code 302Area codes 410, 443, and 667Area code 304/681Area code 804Area code 434Area code 540area codes 240 and 301
Maryland consists of the red and blue areas. The red area indicates area codes 240 and 301. This map is clickable; click on any neighboring area code to go to the page for that code.

North American area codes 240 and 301 are telephone area codes for the western half of Maryland. They serve Maryland's portion of the Greater Washington, D.C., metro area, portions of southern Maryland, and the more rural areas in the western portion of the state. This includes the communities of Cumberland, Frederick, Hagerstown, Gaithersburg, Rockville, Landover and Silver Spring.


The main area code, 301, was one of the original area codes established in 1947, and originally covered the entire state of Maryland. This was despite the fact that, then as now, the bulk of the state's population is split between two very large metropolitan areas–Baltimore and the Washington suburbs. From 1947 to 1990, it was possible for telephone users on the Maryland side of the Washington metropolitan area to dial any number in the region with only seven digits. Although the metro area was split between three area codes–the district's 202, Northern Virginia's 703, and Maryland's 301–it was a single local calling area. Every number on the Maryland and Virginia sides of the metro was given a "hidden" number in the District's 202, essentially using 202 for the entire metro. One consequence of this was that no central office codes could be duplicated in the D.C. area. For instance, if 202-574 was in use in the District or 703-574 was being used in Northern Virginia, the corresponding 301-574 exchange in Maryland could only be used in areas at a safe distance from the Washington metro area, such as the Eastern Shore.

By the end of the 1980s, the Washington metropolitan area was running out of prefixes. In order to free more available numbers, the suburban use of 202 was ended on October 1, 1990. As of that date, local calls from Maryland to either the District of Columbia or Virginia were required to include the area code when dialing. Local calls to Maryland from either the District of Columbia or Virginia also needed to include the area code while dialing. Local calls within Maryland did not require dialing the area code.[1]

Despite the presence of the Baltimore–Washington metropolitan area, 301 remained the exclusive area code for Maryland for 44 years, making Maryland one of the largest states with a single area code. By the end of the 1980s, it was apparent that breaking seven-digit dialing in the Washington area would not free up enough numbers to stave off the immediate need for a new area code. The number shortage was magnified by the fact that most of the Washington metro is a single LATA, meaning that many numbers in the District and Northern Virginia were unavailable for use.

Baltimore and the Eastern Shore were split off as area code 410 on October 6, 1991. The split largely followed metro area lines. However, part of Howard County, which is reckoned as part of the Baltimore area, stayed in 301 while the rest shifted to 410.[2] Normally, when an area code is split, the largest city in the old numbering plan area retains the existing area code—in this case, Baltimore. However, it was decided to let the Washington suburbs keep 301. Not only do the Washington suburbs have the bulk of the state's population,but Bell Atlantic (now Verizon) wanted to spare the large number of federal agencies on the Maryland side of the metro the expense and burden of having to change their numbers.

This was intended as a long-term solution, but within four years 301 was close to exhaustion due to the proliferation of cell phones and pagers, especially in the Washington suburbs. To solve this problem, area code 240 was introduced on June 1, 1997, as the state's first overlay area code.[3] Overlays were a new concept at the time, and met with some resistance due to the requirement for ten-digit dialing. For this reason, conventional wisdom would have suggested a split in which the Washington suburbs would have kept 301 while Frederick and points west would have shifted to 240. However, Bell Atlantic wanted to spare residents, particularly in the more rural western portion, the burden of having to change their numbers.

Area code 227 is scheduled to be overlaid on 301/240 some time in the longer term to provide additional assignable numbers, although the current area codes are not expected to exhaust before 2024.


Counties served by these area codes include:

Local calls require 10-digit dialing (area code + number, leading "1" is not required).


  1. ^ a b c d Four counties were split between area code 301 and 410.
    • Anne Arundel County was assigned area code 410, except Laurel exchanges 210, 317, 490, 497, 498, 596, 604, 725, and 778 and Marlboro exchange 952 remained area code 301.
    • Carroll County was assigned area code 410, except Mount Airy exchange 829 remained area code 301.
    • Howard County was assigned area code 410, except Mount Airy exchange 829 and Laurel exchanges 210, 317, 490, 497, 598, 604, 725, and 776 remained area code 301.
    • Frederick County remained area code 301, except Union Bridge exchange 775 and New Windsor exchange 635 was assigned 410.[4]


  1. ^ Jordan, Mary; Quimpo, Margie G. (September 23, 1990). "Territorial Telephones; On Oct. 1, Local Calls Will Get Complicated". The Washington Post. p. 1.
  2. ^ "Bellcore Letter IL-90/12-049" (PDF). North American Numbering Plan Administration. Neustar. Retrieved June 21, 2013.
  3. ^ "Bellcore Letter IL 96/06-009" (PDF). North American Numbering Plan Administration. Neustar. Retrieved 21 June 2013.
  4. ^ "New area code for eastern Maryland". The Baltimore Sun. November 1, 1991. p. 1A.

External links[edit]

Maryland area codes: 240/301, 410/443/667
North: 223/717, 412/724/878, 814
West: 202, 304/681, 540, 571/703 area codes 240/301 East: 410/443/667
South: 804, 304/681
District of Columbia area codes: 202
Pennsylvania area codes: 215/267/445, 223/717, 272/570, 412, 484/610, 724, 814, 878
Virginia area codes: 276, 434, 540, 571/703, 757, 804
West Virginia area codes: 304/681