What this tool is for
This lookup turns a three-digit US telephone area code into the state or territory it serves, and works the other way too, listing every area code assigned to a state you name. It is handy for verifying caller regions, cleaning phone data, or building dropdowns and validators.
How it works
Every standard US phone number begins with a three-digit area code under the North American Numbering Plan, and each geographic code is assigned to a region within one state. The tool stores that mapping and filters it as you type, matching either the digits of the code or the state name.
Because large states such as California, Texas, New York, and Florida have outgrown a single code, they appear many times, once per area code. Dense metros also use overlays, where several codes cover the same physical area, which is why ten-digit dialing is now the norm in much of the country.
Tips and notes
Use the area code as a reliable signal of the state but not of the exact city. Number portability lets a person keep their number after moving, and overlays mix codes within one region, so the code reflects where the number was first issued. Toll-free and other non-geographic codes are intentionally excluded, since they carry no location, and brand-new codes may lag behind official assignment changes.