| Country | United States |
| State/Province | Maryland |
| Major City | Rockville |
| Time Zone | Eastern (UTC-05:00) |
301 is the area code for Maryland’s portion of the Washington, DC metro area, including portions of southern Maryland, and points northwest of DC. This area encompasses Cumberland, Frederick, Hagerstown, and Gaithersburg. The 301 area code served as the area code for the entire state of Maryland unt
