When did area codes start?

The area codes start in 1947.

The Area Code Telephone System was created in the 1940s by AT&T (American Telephone & Telegraph Company) and Bell Laboratories and become mandatory in 1947.

This numbering system at its foundation was called the North American Numbering Plan (NANP) and applied to the USA and Canada. Initially it had 86 area codes and currently there are 328.

At the time of its creation the area codes were composed of three numbers, currently this remains the same, with the USA area codes having three digits each.