Federal agencies and biotech startups in Bethesda share this exact area code with rural communities near the West Virginia border that were still running manual switchboard systems well into the postwar era. The 240 area code spans one of the most economically lopsided territories in Maryland, stretching from the dense, wealthy DC suburbs all the way to remote mountain counties bordering Pennsylvania and West Virginia.
Western and Southern Maryland, At a Glance
| Category | Details |
| State | Maryland, USA |
| Coverage Area | Rockville, Bethesda, Gaithersburg, Frederick |
| Went Into Service | June 1, 1997 |
| Time Zone | Eastern Time (EST: UTC-5 / EDT: UTC-4) |
| Overlays With | 301, 227 |
| Counties Covered | Montgomery, Frederick, Prince George’s, Allegany, Garrett, Washington |
Maryland’s First Overlay
240 launched on June 1, 1997, becoming Maryland’s very first overlay code, layered directly onto 301’s existing territory rather than dividing the state further. That decision reflected 301’s status as one of America’s original 1947 area codes, one that had covered the entire state of Maryland before Baltimore split away into its own separate code decades earlier.
Federal Suburbs Meeting Appalachian Foothills
This territory’s economic diversity is genuinely striking. Bethesda and Rockville anchor a corridor of federal agencies, healthcare institutions, and biotech companies feeding directly off Washington DC’s proximity. Meanwhile, Garrett and Allegany counties, sitting far to the west near the Pennsylvania and West Virginia borders, represent a considerably more rural, mountainous Maryland, historically slower to modernise their phone infrastructure than the booming DC-adjacent suburbs sharing the same numbering territory.
Where This Code Actually Reaches
240 overlays 301’s territory across a genuinely wide swath of Maryland:
- Bethesda, Rockville, and Potomac in Montgomery County
- Gaithersburg and Germantown, both fast-growing tech corridors
- Frederick and Hagerstown further west
- Waldorf in southern Maryland’s Charles County
Frederick occupies an interesting middle ground within this territory, close enough to the DC metro to draw commuters, yet distinct enough to maintain its own historic downtown character separate from the denser Bethesda-Rockville corridor.
An Economy Anchored by Federal Institutions and Biotech
Montgomery County alone hosts a dense concentration of federal agencies, healthcare research institutions, and technology companies, drawn by proximity to Washington DC without the higher costs of operating directly in the district. That economic weight contrasts sharply with the more agricultural and tourism-driven economies found in Garrett and Allegany counties toward the state’s western edge.
Why 227 Joined as a Third Overlay in 2023
Even after two codes shared this territory for over two decades, continued growth pushed the combined 301/240 numbering pool toward exhaustion, with NANPA projecting the pool would run dry between April and June 2023. Maryland’s Public Service Commission approved 227 as a third overlay in response, selected specifically to serve the identical geographic region without requiring any boundary changes or further splits.
Frequently Asked Questions
Q1. Why does one Maryland area code cover both wealthy DC suburbs and remote rural counties?
When 301 originally split from Baltimore’s territory decades ago, the remaining western Maryland footprint stayed intact as a single numbering region, and subsequent overlays like 240 simply layered onto that same broad geography rather than dividing it by economic character.
Q2. Does it matter whether a Maryland number carries 301, 240, or 227?
No. All three codes overlay identical territory and function completely the same for calls, texts, and business registration, differing only in which happened to be available when a number was assigned.
Q3. Was 240 genuinely the first overlay code ever used in Maryland?
Yes, this is documented. When 240 launched in 1997, it marked Maryland’s first use of the overlay system, setting the precedent that 227 would later follow in the same territory.
Q4. Can a business outside Maryland get a 240 number to establish a presence in this region?
Yes, virtual number providers commonly issue 240, 301, or 227 numbers to businesses anywhere, letting them establish a Maryland presence for federal contracting, biotech, or general business outreach without needing a physical office there.
