There are more than 450 area codes in active use across the North American Numbering Plan (NANP) today, including 50 states, the District of Columbia, Canadian provinces, and several Caribbean territories. The exact count changes constantly because new area codes are assigned as old ones run out of numbers.
The beginning: 86 area codes in 1947
When the North American Numbering Plan was designed in 1947, engineers divided the continent into 86 area codes. The rules were strict: the second digit of an area code had to be 0 or 1, because those digits were reserved for operator and long-distance services. States with larger populations received multiple codes; smaller states shared one.
Why the count grew so fast
Each area code holds a maximum of roughly 8 million telephone numbers (about 10 million possible, minus reserved ranges). As population, second phone lines, fax machines, and mobile phones exploded, entire regions exhausted their blocks. The result:
- Splits — an existing area code is divided, and one region gets a new code.
- Overlays — a second code is added to the same geography, making 10-digit dialing mandatory in that region.
- Today, large states like California and Texas each have dozens of area codes.
How new area codes are assigned
The assignment process is managed by the North American Numbering Plan Administration (NANPA), working with state telecommunications regulators and telecom providers:
- Exhaustion forecast — carriers project when a region will run out of numbers.
- Planning — regulators decide between a split and an overlay.
- Implementation — a new code is opened, with a mandatory permissive dialing period during which both old and new codes work.
- Customer notification — phone numbers, publications, and alarm systems are updated across the affected region.
Where to look up any area code
Because the numbering plan evolves constantly, the authoritative way to check any prefix is to look it up against current NANPA and telecom data. Our area code directory tracks every NPA, its region, timezone, and overlay codes, plus up-to-date scam warnings for high-risk prefixes.