Maryland area codes

Codes in service in Maryland

Maryland has 6 geographic area codes in service: 227, 240, 301, 410, 443, 667. 301 is the oldest, dated 1947, and 227 the newest, dated 14 Jun 2023.1 All of Maryland's codes are on Eastern time.

Area code	NANPA location	NPA in-service date	In-service overlay peers	Time zone	Local calls within the code
227	MD	14 Jun 2023	240, 301	Eastern	10 digits
240	MD	1 Jun 1997	227, 301	Eastern	10 digits
301	MD	1947	240, 227	Eastern	10 digits
410	MD	6 Oct 1991	443, 667	Eastern	10 digits
443	MD	1 Jun 1997	410, 667	Eastern	10 digits
667	MD	24 Mar 2012	410, 443	Eastern	10 digits

Scroll the table sideways to see every column. Sources: NANPA (14 October 2026 file).

History and overlays in Maryland

Before 1960: 301 (1947)
1990s: 410 (6 Oct 1991), 240 (1 Jun 1997), 443 (1 Jun 1997)
2010s: 667 (24 Mar 2012)
2020s: 227 (14 Jun 2023)

Maryland's in-service overlay groups are 227/240/301; 410/443/667.1

227/240/301: 301 (1947) was joined by 240 on 1 Jun 1997 and 227 on 14 Jun 2023.
410/443/667: 410 (1991) was joined by 443 on 1 Jun 1997 and 667 on 24 Mar 2012.

Dialing in Maryland

Local calls within a single area code in Maryland (227, 240, 301, 410, 443, 667) are all recorded as 10 digits. From any of Maryland's codes, local calls to another area code are all recorded as 10 digits.1

Neighbours of Maryland

Regions that border Maryland:

Delaware: 1 code (302)
District of Columbia: 2 codes (202, 771)
Pennsylvania: 15 codes (215, 223, 267, 272, ...)
Virginia: 10 codes (276, 434, 540, 571, ...)

Rules that apply to every region are on the area-code reference.

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Sources

Every regulatory and pricing claim on this page links to the primary source it came from. Figures were checked on the date shown at the top of the page; rules and prices change, so verify before relying on one.

NANPA, NPA Database CSV, file dated 14 October 2026; US geographic codes, location, dates, overlay complexes, dialing plan and time zone. Retrieved 14 Oct 2026
https://reports.nanpa.com/public/npa_report.csv