The area code 240 is located in Aspen Hill, Maryland.
Area code 240 serves Aspen Hill, Maryland, a community in Montgomery County just north of Washington, D.C. It is an overlay of the long-standing 301 area code, created in 1997 to add more phone numbers for the fast-growing region. With the 240/301 overlay, residents and businesses in Aspen Hill use 10‑digit dialing for local calls. The area connects to major corridors like Georgia Avenue and Connecticut Avenue, linking Aspen Hill to nearby hubs across the D.C. metro area.
“Area code 240 was introduced in 1997 as an overlay of 301, requiring 10-digit local dialing.” — North American Numbering Plan Administrator (NANPA)
Major nearby cities and landmarks in the 240/301 service area include:
The 240 and 301 area codes cover much of suburban D.C. as well as western and southern Maryland, so phone numbers in Aspen Hill often appear alongside those from nearby cities. Fun fact: 301 is one of the original area codes from 1947, and 240 expanded the numbering pool without changing existing numbers. This overlay setup helps keep local identity while supporting new mobile lines, businesses, and services. If you see a 240 phone number in Aspen Hill, it’s part of the same calling region as 301, serving everyday life across Montgomery County.