240 Area Code: Maryland | Location & Time Zone

The 240 area code serves western Maryland, including major metropolitan areas in Montgomery County, Frederick County, and the greater Washington D.C. region. This area code was introduced on June 1, 1997, as an overlay for the existing 301 area code to meet growing telecommunications demand in the region. Understanding the 240 area code is essential for residents, businesses, and visitors navigating Maryland’s telecommunications landscape.

What is the 240 Area Code?

The 240 area code is an overlay area code that covers the same geographic territory as area code 301 in western Maryland. It was established on June 1, 1997, as Maryland’s first overlay area code to address number exhaustion in the rapidly growing Washington D.C. metropolitan area. This overlay system requires ten-digit dialing for all local calls within the region, even when calling within the same area code.

The 240 area code serves Maryland’s portion of the Greater Washington D.C. metro area, portions of southern Maryland, and rural western Maryland communities. In June 2023, area code 227 was added as a third overlay to provide additional number capacity for the region.

240 Area Code Location & Coverage

Cities and Regions Covered

The 240 area code encompasses numerous major cities and communities throughout western Maryland, including Rockville, Gaithersburg, Germantown, Silver Spring, Frederick, Hagerstown, Bethesda, and Potomac. Other significant communities include Cumberland, Waldorf, College Park, Greenbelt, Landover, and Montgomery Village.

The coverage area includes all of Allegany, Charles, Garrett, Montgomery, Prince George’s, St. Mary’s, and Washington counties, most of Frederick County, western Howard County, and portions of southwestern Carroll County and western Anne Arundel County.

Geographic Coverage

The 240 area code region is characterized by diverse landscapes, from the Appalachian Mountains in the west to the Potomac River in the south. This area includes both densely populated suburban communities near Washington D.C. and rural towns throughout western Maryland’s mountainous regions.

Time Zone Information

The 240 area code operates in the Eastern Time Zone, observing both Eastern Standard Time (UTC-5) during winter months and Eastern Daylight Time (UTC-4) during daylight saving time.

240 Area Code Details

History of 240 Area Code

When Was 240 Created?

Area code 301 was one of the original North American area codes, established in 1947 to serve all of Maryland. In 1991, the eastern portion of Maryland was split off to create area code 410, serving Baltimore and the Eastern Shore, while 301 continued to serve western Maryland.

By the mid-1990s, area code 301 was approaching number exhaustion due to rapid population growth and the proliferation of cell phones and pagers in the Washington D.C. suburbs. Area code 240 was implemented on June 1, 1997, as an overlay solution to provide additional numbering capacity without requiring customers to change their existing phone numbers.

Area Code Changes and Overlays

The implementation of 240 marked Maryland’s first use of overlay technology, which was a relatively new concept at the time and met with some resistance due to the requirement for ten-digit dialing. Most recently, area code 227 was added as a third overlay on June 14, 2023, to address continued number demand in the region.

How to Call 240 Area Code

Dialing Within the Area Code

Ten-digit dialing is mandatory for all calls within the 240 area code region. When making local calls, dial: 240-XXX-XXXX. The leading “1” is not required for local calls within the area.

Dialing From Other Area Codes

When calling a 240 number from outside the local area, use the format: 1-240-XXX-XXXX. This applies to all long-distance calls to 240 area code numbers from other regions.

International Dialing

International callers should use the format: +1-240-XXX-XXXX when dialing 240 area code numbers from outside the United States.

Nearby Area Codes

Much of the Washington metropolitan area operates as a local calling area, with some 240 area code locations like Rockville, Gaithersburg, and Bethesda remaining local calls to Washington D.C. and Northern Virginia.

Population & Demographics

The 240 area code region serves a population of approximately 4.7 million people across its coverage area. This region includes some of the most affluent and educated communities in the United States, with Montgomery County being one of the wealthiest counties in Maryland.

The area is characterized by strong economic growth, with major employers including the National Institutes of Health, Lockheed Martin, and Marriott International. The region benefits from its proximity to the federal government and the broader Washington D.C. metropolitan economy.

Frequently Asked Questions

Do I need to dial the area code for local calls in the 240 area code?

Yes, ten-digit dialing is required for all calls within the 240 area code region, including local calls. This requirement exists because 240 is an overlay area code that shares the same geographic territory with area codes 301 and 227.

What cities are included in the 240 area code?

Major cities in the 240 area code include Rockville, Gaithersburg, Germantown, Silver Spring, Frederick, Hagerstown, Bethesda, Potomac, Cumberland, and Waldorf, among many others.

When was the 240 area code established?

Area code 240 was established on June 1, 1997, as an overlay for the existing 301 area code. It was created to address the growing demand for phone numbers in western Maryland.

What other area codes serve the same region as 240?

Area codes 301 and 227 also serve the same geographic region as 240. Area code 301 is the original code from 1947, while 227 was added in 2023 as the newest overlay.

What time zone is the 240 area code in?

The 240 area code is located in the Eastern Time Zone, observing Eastern Standard Time (EST) and Eastern Daylight Time (EDT).

Conclusion

The 240 area code represents an important part of Maryland’s telecommunications infrastructure, serving the dynamic western Maryland region including major suburbs of Washington D.C. Since its implementation in 1997, the 240 area code has successfully provided additional numbering capacity for one of the fastest-growing regions in the Mid-Atlantic. Whether you’re a resident, business owner, or visitor, understanding the 240 area code’s coverage, time zone, and dialing requirements helps ensure seamless communication throughout this vibrant part of Maryland.

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