Maryland has 6 active area codes serving its diverse communities across the Eastern Time Zone. The state uses two distinct overlay complexes: 227/240/301 covering western Maryland and the Greater Washington D.C. metro area, and 410/443/667 serving eastern Maryland, including Baltimore and the Eastern Shore.
Whether you need to identify an unknown caller, schedule business calls, or understand Maryland’s telephone system, this guide provides complete and current information about every Maryland area code.
Quick Reference Table: Maryland Area Codes
| Area Code | Primary Cities/Regions | Time Zone | Type | Year Introduced |
|---|---|---|---|---|
| 301 | Germantown, Silver Spring, Rockville, Frederick, Gaithersburg | Eastern (EST/EDT) | Original | 1947 |
| 240 | Same as 301 (Western MD overlay) | Eastern (EST/EDT) | Overlay | 1997 |
| 227 | Same as 301/240 (Western MD overlay) | Eastern (EST/EDT) | Overlay | June 2023 ⚠️ |
| 410 | Baltimore, Annapolis, Columbia, Glen Burnie | Eastern (EST/EDT) | Split from 301 | 1991 |
| 443 | Same as 410 (Eastern MD overlay) | Eastern (EST/EDT) | Overlay | 1997 |
| 667 | Same as 410/443 (Eastern MD overlay) | Eastern (EST/EDT) | Overlay | 2012 |
Maryland's Two Area Code Regions
Maryland is divided into two distinct telecommunications regions, each with its own overlay complex serving the same geographic area.
Western Maryland (227/240/301 Complex):
This region covers the Greater Washington D.C. metro area, including Montgomery County, Prince George’s County, and extends west to Cumberland and Hagerstown. All three area codes serve identical geographic territory. Major cities include Bethesda, Silver Spring, Germantown, Frederick, Rockville, Waldorf, and Wheaton.
This region is heavily influenced by federal government presence and includes major employers like the National Institutes of Health and numerous federal agencies.
Eastern Maryland (410/443/667 Complex):
This region encompasses Baltimore City, the Baltimore metropolitan area, Annapolis, and the entire Eastern Shore extending to the Atlantic coast. All three codes cover the same geographic area without distinction. Key cities include Baltimore, Columbia, Annapolis, Glen Burnie, Ellicott City, and Salisbury.
This region centers around Baltimore’s economy, including Johns Hopkins University, the Port of Baltimore, and diverse industries from healthcare to cybersecurity.
The boundary between these regions generally follows a line running southeast from the Pennsylvania border near the Susquehanna River, crosses the Chesapeake Bay, and terminates near the Virginia line west of Calvert County.
Detailed Area Code Information
301 - Maryland's Original Area Code
Area code 301 was established in 1947 as one of the original 86 North American area codes, initially covering the entire state of Maryland. This made it one of the most populous single-area-code states for over four decades. In 1991, Baltimore and the Eastern Shore split off as area code 410, leaving 301 to serve western and southern Maryland.
Geographic Coverage: Western Maryland, including Montgomery County, Prince George’s County, Frederick County, Washington County, Allegany County, Garrett County, Charles County, St. Mary’s County, western Howard County, and portions of Carroll and Anne Arundel counties.
Major Cities: Germantown, Silver Spring, Rockville, Frederick, Gaithersburg, Bethesda, Waldorf, Wheaton, Hagerstown, Bowie, and Cumberland.
Population Served: Approximately 3.1 million residents across the Greater Washington D.C. metro area and western Maryland communities.
Why Created: As Maryland’s first area code, 301 was assigned during the original implementation of the North American Numbering Plan to standardize long-distance dialing nationwide.
Special Notes: Many federal agencies and institutions retained 301 numbers during the 1991 split to avoid the expense and disruption of changing telephone numbers. The region is home to one of the nation’s wealthiest and most educated populations.
240 - First Maryland Overlay
Area code 240 was introduced on June 1, 1997, as Maryland’s first overlay, serving the exact same geographic region as 301. This implementation met some resistance at the time because it introduced the then-new concept of overlay area codes and required 10-digit dialing for all local calls.
Geographic Coverage: Identical to 301, covering all of western Maryland and the Washington D.C. metro suburbs.
Major Cities: Same cities as 301, including Bethesda, Silver Spring, Germantown, Frederick, Rockville, and dozens of other communities.
Population Served: Approximately 3.1 million (shared with 301 and 227).
Why Created: By the mid-1990s, the 301 area code was approaching exhaustion due to the proliferation of cell phones, pagers, and fax machines, particularly in the Washington suburbs. The overlay solution avoided forcing 1.2 million people to change their phone numbers.
Special Notes: When 240 was introduced, it was predicted to provide relief until 2008, but demand exceeded projections. The overlay requires mandatory 10-digit dialing for all calls, even within the same area code.
227 - Maryland's Newest Area Code ⚠️
IMPORTANT UPDATE: Area code 227 was introduced on June 14, 2023, making it Maryland’s most recent addition to its telephone numbering system.
Geographic Coverage: Identical to 301 and 240, serving western Maryland including Aspen Hill, Bethesda, Bowie, Frederick, Gaithersburg, Germantown, Hagerstown, Potomac, Silver Spring, Waldorf, Wheaton, and many other communities.
Major Cities: Same as 301/240 overlay complex.
Population Served: Approximately 3.1 million (shared with 301 and 240).
Why Created: The Maryland Public Service Commission approved the 227 overlay to ensure a continuing supply of telephone numbers after projections showed the 301/240 region would exhaust available numbers in the second quarter of 2023.
How It Works: The 227 overlay does not require anyone to change their existing area code or phone number. New customers requesting service or additional lines may be assigned numbers in the new 227 area code once existing 240 and 301 numbers are fully allocated.
Special Notes: Customers with 227 numbers dial exactly the same way as those with 301 or 240 numbers. All three codes are completely equal with no geographic distinction. The introduction of 227 adds millions of new possible phone numbers to support the region’s continued growth.
410 - Eastern Maryland's Primary Code
Area code 410 was created on October 6, 1991, in a split from the original 301 that had served all of Maryland since 1947. The split was designed to provide long-term relief for Maryland’s growing telecommunications needs.
Geographic Coverage: Eastern Maryland, including Baltimore City, Baltimore County, Anne Arundel County, Harford County, Howard County (eastern portion), Carroll County (most of), the entire Eastern Shore (9 counties from Cecil to Worcester), and extending south to Calvert County.
Major Cities: Baltimore, Columbia, Annapolis, Glen Burnie, Ellicott City, Dundalk, Towson, Salisbury, Bel Air, Aberdeen, Cambridge, Ocean City.
Population Served: Approximately 3.1 million residents across eastern Maryland.
Why Created: By the late 1980s, Maryland’s 301 area code was on the verge of exhaustion due to rapid growth in the Baltimore and Washington suburbs. The split separated Baltimore and the Eastern Shore (410) from Washington suburbs and western Maryland (301).
Special Notes: Although Baltimore was the state’s largest city, Bell Atlantic (now Verizon) chose to assign it the new 410 code rather than letting it keep 301, primarily to spare federal agencies in the Washington area from having to change numbers. Within five years, 410 was already approaching exhaustion.
443 - First Eastern Maryland Overlay
Area code 443 was overlaid onto the 410 territory on June 1, 1997, less than six years after 410 was created. This was a response to the rapid proliferation of mobile phones and pagers in the Baltimore area.
Geographic Coverage: Identical to 410, covering all of eastern Maryland from Baltimore to the Eastern Shore.
Major Cities: Same cities as 410, including Baltimore, Annapolis, Columbia, and all Eastern Shore communities.
Population Served: Approximately 3.1 million (shared with 410 and 667).
Why Created: Within five years of the 410 split, the area code was already close to exhaustion due to the proliferation of cell phones and pagers. The overlay solution kept residents from having to change their numbers for the second time in less than a decade.
Special Notes: When first introduced, 443 numbers were primarily used by cell phone carriers and competitive local exchange carriers (CLECs) like Comcast, but have since become universal in carrier availability with no distinction from 410 numbers.
667 - Second Eastern Maryland Overlay
Area code 667 was implemented on March 24, 2012, as the third code serving eastern Maryland. This addition was projected to provide numbering resources until approximately 2030.
Geographic Coverage: Identical to 410 and 443, covering all of eastern Maryland.
Major Cities: Same as 410/443 overlay complex.
Population Served: Approximately 3.1 million (shared with 410 and 443).
Why Created: By 2011, the 410/443 area was once again running out of numbers because of the continued proliferation of cell phones and VoIP services. Adding a third overlay code spared residents from another number change.
Special Notes: The 667 overlay assigned 24 million numbers to serve just over 4 million people. Current projections suggest a fourth area code will not be required in this region until around 2030.
Understanding Time Zones in Maryland
Maryland operates entirely within the Eastern Time Zone (ET). The entire state follows Eastern Standard Time (EST) during the winter months and Eastern Daylight Time (EDT) during the summer months.
Current Time: Eastern Time (ET)
UTC Offset: UTC-5 (EST) / UTC-4 (EDT)
Daylight Saving Time: Maryland observes Daylight Saving Time, shifting clocks forward one hour in March and back one hour in November.
Unlike some neighboring states, Maryland has no counties or regions that observe different time zones. Whether you’re calling Baltimore in the east or Cumberland in the west, you’re always calling the same time zone. This simplifies scheduling and eliminates confusion when making calls within the state.
Maryland Cities and Their Area Codes
Here are Maryland’s largest cities with their corresponding area codes:
- Baltimore (585,708) – 410/443/667
- Columbia (104,681) – 410/443/667
- Germantown (91,249) – 301/240/227
- Silver Spring (81,773) – 301/240/227
- Waldorf (81,410) – 301/240/227
- Glen Burnie (72,891) – 410/443/667
- Ellicott City (75,947) – 410/443/667
- Frederick (78,171) – 301/240/227
- Dundalk (67,796) – 410/443/667
- Rockville (67,117) – 301/240/227
- Bethesda (68,056) – 301/240/227
- Gaithersburg (69,657) – 301/240/227
- Bowie (58,329) – 301/240/227
- Annapolis (40,812) – 410/443/667
- Wheaton (50,418) – 301/240/227
How to Use Area Codes in Maryland
Local Dialing Requirements: Maryland requires 10-digit dialing for all calls, even when calling within the same area code. You must always dial the area code plus the seven-digit phone number.
Calling Within Maryland:
- From any Maryland number: Dial area code + 7-digit number
- Example: 410-555-1234
- No need to dial “1” first for local calls
Calling Maryland from Outside the State:
- From elsewhere in the US: Dial 1 + area code + 7-digit number
- Example: 1-410-555-1234
International Dialing to Maryland:
- From outside North America: Dial your country’s exit code + 1 + area code + 7-digit number
- Example from UK: 00-1-410-555-1234
Important Notes:
- Always include the area code when giving out your Maryland phone number
- Save contacts with full 10-digit numbers to ensure calls connect properly
- Overlay areas (all of Maryland) always require 10-digit dialing, even for neighbors on the same street
Frequently Asked Questions
How many area codes does Maryland have?
Maryland currently has 6 active area codes: 301, 240, 227, 410, 443, and 667. These are organized into two overlay complexes serving different regions of the state.
What time zone is Maryland in?
Maryland operates entirely within the Eastern Time Zone (ET). The state observes Eastern Standard Time (EST, UTC-5) in winter and Eastern Daylight Time (EDT, UTC-4) in summer. All Maryland area codes share the same time zone.
Do I need to dial the area code for local calls in Maryland?
Yes. Maryland requires mandatory 10-digit dialing for all calls, including local calls within the same area code. You must dial the area code plus the seven-digit phone number, but you do not need to dial “1” first for local calls.
What is the oldest area code in Maryland?
Area code 301 is Maryland’s oldest, established in 1947 as one of the original 86 North American area codes. It originally covered the entire state until 1991.
What areas does Maryland area code 240 cover?
Area code 240 covers western Maryland and the Greater Washington D.C. metro area, including Montgomery County, Prince George’s County, Frederick, Hagerstown, and surrounding communities. It serves the exact same geographic region as area codes 301 and 227 in an overlay configuration. Cities include Bethesda, Silver Spring, Germantown, Rockville, Gaithersburg, Waldorf, Wheaton, Bowie, and Frederick.
When were Maryland area codes 410 and 301 created?
Area code 301 was created in 1947 as one of the original area codes and initially served all of Maryland. Area code 410 was created on October 6, 1991, when Maryland split into two area codes to address number exhaustion. The 410 code was assigned to Baltimore, the Eastern Shore, and surrounding areas, while 301 continued serving western and southern Maryland.
What's the difference between area codes 410, 443, and 667?
There is no geographic difference between these three area codes. All three serve identical territory in eastern Maryland as overlay codes. Area code 410 was the original (1991), while 443 (1997) and 667 (2012) were added as overlays when more phone numbers were needed. A phone number with any of these codes has the same local calling area and no distinction in service or location. The only difference is when each code was introduced.
Are there other overlays for the 301 area code besides 227?
Yes. Area code 240 has been overlaying 301 since 1997, and 227 was added as a second overlay in June 2023. All three codes (227, 240, and 301) serve the exact same geographic region in western Maryland with no distinctions. When you receive a new phone line in this area, you might be assigned a number from any of these three area codes, depending on availability.
Are new area codes planned for Maryland?
Current projections indicate that the eastern Maryland region (410/443/667) will not require a fourth area code until approximately 2030. The western Maryland region (227/240/301) recently added the 227 overlay in June 2023, which should provide numbering resources for many years. The Maryland Public Service Commission monitors number utilization and announces new area codes well in advance when needed.
Will my phone number change with the new 227 area code?
No. The 227 area code overlay does not require anyone to change their existing area code or phone number. If you currently have a 301 or 240 number, you will keep it. Only new customers requesting service or additional lines may be assigned numbers in the new 227 area code.
Why does Maryland use overlay area codes instead of geographic splits?
Overlays prevent millions of people from having to change their phone numbers, which can be expensive and disruptive for businesses and individuals. With an overlay, multiple area codes serve the same geographic region, and new numbers are assigned from whichever code has availability. The tradeoff is that everyone must use 10-digit dialing for all calls, even local ones.
Can I choose which Maryland area code I get?
When requesting new phone service, you can often request a preference for a specific area code, though availability depends on your service provider and which numbers are currently available. Business VoIP services typically offer more flexibility in choosing area codes, including codes from regions where you may not physically be located.
How do area codes affect my business in Maryland?
Having a local Maryland area code can significantly improve customer trust and response rates. Customers are more likely to answer calls from familiar local area codes rather than unfamiliar or out-of-state numbers. Many businesses operating in Maryland choose numbers with 301, 410, or other Maryland codes, even if they’re physically located elsewhere.
Additional Resources
- Maryland Public Service Commission – Official regulatory authority for Maryland telecommunications
- North American Numbering Plan Administration (NANPA) – Official area code database and assignments
- Federal Communications Commission (FCC) – Federal telecommunications regulations