List of North American Numbering Plan area codes

The North American Numbering Plan (NANP) divides the territories of its members into geographic numbering plan areas (NPAs). Each NPA is identified by one or more numbering plan area codes (NPA codes, or area codes), consisting of three digits that are prefixed to each local telephone number having seven digits. A numbering plan area with multiple area codes is called an overlay. Area codes are also assigned for non-geographic purposes. The rules for numbering NPAs do not permit the digits 0 and 1 in the leading position.^[1] Area codes with two identical trailing digits are easily recognizable codes (ERC). NPAs with 9 in the second position are reserved for future format expansion.