240 Area Code 🌍☎️

The most populous cities in area code 240 are: Mount Rainier, Frederick, Laurel, Rockville, and Silver Spring.

Other cities in the 240 area code include: Hagerstown, Bethesda, Gaithersburg, Cabin John, Hyattsville, Waldorf, Sandy Spring, Cumberland, Beltsville, Capitol Heights, Leonardtown, Columbia, Glenn Dale, Oxon Hill, College Park, Chevy Chase, Myersville, Kensington, Great Mills, Damascus, Hughesville, Upper Marlboro, Montgomery Village, Clinton, La Plata, Brandywine, Mechanicsville, Ridge, Poolesville, Newburg, Indian Head, Oakland, Mount Airy, Westernport, Nanjemoy, Clarksville, Hancock, Adamstown, Emmitsburg, Williamsport, Grantsville, Clear Spring, Cascade, Thurmont, Middletown, Smithsburg, Greenbelt, Frostburg, Brunswick, Walkersville, Lonaconing, Keedysville, Kitzmiller, Friendship, Bittinger, Lexington Park, Odenton, Crofton, Ijamsville, District Heights, Temple Hills, New Market, Mount Savage, Friendsville, Flintstone, Baltimore, Tall Timbers, and Ashton.

Mount Rainier / r eɪ ˈ n ɪər / is a city in Prince George's County, Maryland, United States. The population was 8,080 at the 2010 census. Bordering Washington, D.C., Mount Rainier got its start as a streetcar suburb. (See Streetcars in Washington, D.C.) According to local tradition, surveyors from the Pacific Northwest named the town, giving the streets names such as " Shasta " and " Cascade ". Historic U.S. 1 runs through the center of the town and serves as the main street and central business district.

Frederick is a city and the county seat of Frederick County in the U.S. state of Maryland. It is part of the Baltimore–Washington Metropolitan Area. Frederick has been an important crossroads community since it was located in colonial times at the intersection of an important north–south Indian trail, and east–west routes to the Chesapeake Bay both at Baltimore and what became Washington, D.C. and across the Appalachian mountains to the Ohio River watershed. It is a part of the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area, which is part of a greater Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area. The city's population was 65,239 people at the 2010 United States Census, making it the second-largest incorporated city in Maryland, behind Baltimore.Frederick is home to Frederick Municipal Airport (IATA : FDK), which primarily accommodates general aviation traffic, and to the county's largest employer U.S. Army's Fort Detrick bioscience/communications research installation.

Laurel is a city in northern Prince George's County, Maryland, in the United States, located midway between Washington, D.C., and Baltimore on the Patuxent River. Founded as a mill town in the early 19th century, the arrival of the Baltimore & Ohio Railroad in 1835 expanded local industry and later enabled the city to become an early commuter town for Washington and Baltimore workers. Largely residential today, the city maintains a historic district centered on its Main Street, highlighting its industrial past.The Department of Defense is a prominent presence in the Laurel area today, with the Fort Meade Army base, the National Security Agency, and Johns Hopkins University's Applied Physics Laboratory all located nearby. Laurel Park, a thoroughbred horse racetrack, is located just outside city limits.

The 240 area code lies within the Eastern Daylight Time Zone (or EDT). The current time in Eastern Daylight Time is 09:39 PM on Apr 29, 2025.

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