240 Area Code 🌍☎️

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

Other cities in the 240 area code include: Hagerstown, Mount Rainier, Gaithersburg, Cabin John, Hyattsville, Waldorf, Sandy Spring, Cumberland, Beltsville, Capitol Heights, Leonardtown, Glenn Dale, College Park, Columbia, Oxon Hill, Clinton, Kensington, Great Mills, Damascus, Myersville, Upper Marlboro, Hughesville, La Plata, Brandywine, Chevy Chase, Mechanicsville, Ridge, Poolesville, Montgomery Village, 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, Roanoke, Odenton, Crofton, Ijamsville, District Heights, Temple Hills, New Market, Mount Savage, Friendsville, Flintstone, Baltimore, Tall Timbers, and Ashton.

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.

Rockville is a city located in the central region of Montgomery County, Maryland. It is the county seat and is a major incorporated city of Montgomery County and forms part of the Baltimore–Washington metropolitan area. The 2010 census tabulated Rockville's population at 61,209, making it the third largest incorporated city in Maryland, behind Baltimore and Frederick. Rockville is the largest incorporated city in Montgomery County, Maryland, although the nearby census-designated place of Germantown is more populous. Rockville, along with neighboring Gaithersburg and Bethesda, is at the core of the Interstate 270 Technology Corridor which is home to numerous software and biotechnology companies as well as several federal government institutions. The city also has several upscale regional shopping centers and is one of the major retail hubs in Montgomery County.

The 240 area code lies within the Eastern Daylight Time Zone (or EDT). The current time in Eastern Daylight Time is 07:20 AM on Mar 10, 2026.