https://en.wikipedia.org/wiki/North_American_Numbering_Plan

https://en.wikipedia.org/wiki/Original_North_American_area_codes

See also: https://en.wikipedia.org/wiki/Area_Codes_(Ludacris_song)#Cultural_legacy

a cultural critic has noted that the core conceit of the “Area Codes” song may become confusing to future generations of listeners not raised with the concept that a particular area code must be tied to residence in a particular region and not knowledgeable about the assigned area code numbering for major urban areas