Maryland · Eastern Time
301 Area Code
Area code 301 is in Maryland, serving western Maryland and the Washington, D.C. suburbs in Montgomery and Prince George's counties. It is in the Eastern Time zone. It shares its territory with overlay codes 227 and 240, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 301 area code?
301 is a Maryland area code covering western Maryland and the Washington, D.C. suburbs in Montgomery and Prince George's counties. In the wider directory it sits in the South region.
Cities in the 301 area code
- Frederick
- Rockville
- Gaithersburg
- Germantown
- Silver Spring
- Bethesda
- Hagerstown
- Bowie
- Waldorf
- College Park
- Laurel
- Greenbelt
- Cumberland
- Upper Marlboro
Counties served by 301
Montgomery County, Prince George's County, Frederick County, Washington County, Charles County, Allegany County, St. Mary's County and Garrett County.
301 overlay codes and dialing
The 301 territory is covered by an overlay of 3 area codes: 227, 240, 301. All of them serve the same geographic area, and the original code is 301. Because more than one code covers the same ground, 10-digit dialing is mandatory — you must dial the area code for every local call. New phone lines may be assigned any of these codes.
History of the 301 area code
301 is one of the original area codes assigned in 1947, when AT&T and Bell Laboratories created the North American Numbering Plan and divided the country into the first 86 numbering plan areas. It has served the Frederick area ever since, with 227 and 240 later added as overlays to supply more numbers.
Is 301 a scam or spam risk?
301 is a legitimate geographic area code, not a premium or toll line, so a call from it costs you nothing extra. That said, scammers frequently spoof real local area codes to look familiar on caller ID. A genuine 301 number on your screen is no guarantee the caller is in Frederick, MD or trustworthy. See spam & scam-risk area codes for how spoofing works and how to respond.
Explore more
See every code in Maryland, compare codes across the South region, or view all Eastern Time codes. You can also browse the 3XX block or the complete numeric list of US area codes.
New to how this all works? Start with how area codes work, then read up on overlays, 10-digit dialing, and spam & scam-risk codes. To check another number, use the area code lookup tool.
Quick answers
301 area code FAQ
Where is the 301 area code?
The 301 area code is in Maryland, covering western Maryland and the Washington, D.C. suburbs in Montgomery and Prince George's counties, in the South region.
What cities are in the 301 area code?
Cities in the 301 area code include Frederick, Rockville, Gaithersburg, Germantown, Silver Spring, Bethesda, Hagerstown, Bowie, Waldorf and College Park.
What time zone is 301 in?
301 is in the Eastern Time zone.
What is the overlay for the 301 area code?
301 shares its territory with 227 and 240. All 3 codes (227, 240, 301) serve the same area, so 10-digit dialing is required for every call.
When did the 301 area code start?
301 went into service on January 1, 1947 as one of the original 1947 North American area codes.
Do I have to dial 10 digits for 301?
Yes. Because 301 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 301 a toll-free or premium code?
No. 301 is a standard geographic area code, so calling it costs the same as any local or long-distance call on your plan. Toll-free calls use 800, 888, 877, 866, 855, 844 or 833.