301 Area Code — Rockville, MD
Area code 301 serves Rockville and 4 other cities in Maryland. Local time follows America/New_York. It overlays with 240, so 10-digit dialling is required.
- State
- Maryland
- Primary city
- Rockville
- Timezone
- America/New_York
- In service since
- 1947
- Type
- Geographic
- Overlay codes
- 240
Cities Served by 301
The 301 area code covers 5 cities and communities in Maryland.
- Rockville
- Silver Spring
- Bethesda
- Frederick
- Gaithersburg
About Area Code 301
Area code 301 is a North American Numbering Plan (NANP) area code that has been in service since 1947. It is administered by NANPA on behalf of the FCC and serves the Maryland region anchored on Rockville.
301 now shares its territory with an overlay code (240). 10-digit dialling is required for local calls within this region because the same 7-digit number can be assigned under either code.
Mobile numbers in 301 are portable: a person who moved away from Rockville may still carry a 301 mobile number on their device. If you receive an unexpected call from a 301 number, run it through the reverse lookup tool above for the most accurate, free identification.
If you live or do business in Maryland, you may also interact with neighbouring or overlay codes (240). See the related codes section below to explore the rest of Maryland.
Other Maryland Area Codes
Continue exploring the Maryland numbering plan.
301 Area Code FAQ
Where is area code 301?
Area code 301 is located in Maryland, primarily serving Rockville and surrounding cities including Silver Spring, Bethesda, Frederick. The region operates on ET (America/New_York) time.
What state is 301 area code?
301 is a Maryland area code. It was put into service in 1947 and shares its geographic footprint with overlay code 240.
Is 301 a scam area code?
301 is a legitimate North American area code allocated by NANPA to Maryland. Like any geographic area code, scammers sometimes spoof 301 numbers — judge each call by content (urgent demands, unfamiliar transfers) rather than the area code alone. Run the specific number through our reverse lookup if you're unsure.
What time zone does 301 use?
Area code 301 operates on ET (America/New_York). Numbers in this area code follow standard Maryland time-zone rules including any daylight-saving transitions for that region.
Can I look up a specific 301 phone number?
Yes. Use the reverse lookup widget above to enter a full 301 number. NumLocation returns the line type (mobile, landline, VoIP), carrier, rate-center city, and any public listings tied to the number — free.
What's the difference between 301 and 240?
301 and 240 cover the same Maryland geographic area as overlay codes. Calls between them are local, but you must dial all 10 digits. New phone numbers in this region are assigned from either pool depending on what's available with the carrier at signup.