List of Maryland area codes
The state of Maryland is served in two geographically distinct numbering plan areas in the North American Numbering Plan, which are each served with three overlay area codes.
| Area code | Year created | Parent NPA | Overlay | Numbering plan area |
| 301 | 1947 | – | 227/240/301 | Western Maryland, including its suburbs of Washington, D.C. |
| 240 | 1997 | 301 | 227/240/301 | Western Maryland, including its suburbs of Washington, D.C. |
| 227 | 2023 | 240/301 | 227/240/301 | Western Maryland, including its suburbs of Washington, D.C. |
| 410 | 1991 | 301 | 410/443/667 | Eastern Maryland including Baltimore and Annapolis |
| 443 | 1997 | 410 | 410/443/667 | Eastern Maryland including Baltimore and Annapolis |
| 667 | 2012 | 410/443 | 410/443/667 | Eastern Maryland including Baltimore and Annapolis |
Area code list
Maryland
Area codes