Area Code Lookup
What Area Code Is Washington Zone 4?
2 area codes serve Washington Zone 4 · Maryland
Washington Zone 4 is served by area codes 240, 301. It is located in Maryland.
Area Codes Serving Washington Zone 4
Frequently Asked Questions
What area code is Washington Zone 4?
Washington Zone 4 is served by area codes 240, 301. It is located in Maryland.
Why does Washington Zone 4 have multiple area codes?
As demand for phone numbers increased, NANPA added area codes through splits (dividing the region) or overlays (layering a new code over the same geography). Washington Zone 4 now has 2 area codes — 240 and 301 — covering the same or overlapping areas.
How do I call Washington Zone 4 from outside the US?
To call Washington Zone 4 from abroad, dial +1 followed by the area code and 7-digit local number (e.g. +1-240-XXX-XXXX). The +1 is the country code for all NANPA countries.