The 411 on the 313

by Vince Carducci

In these postmodern times, the combination of numbers "313," the area code of the city of Detroit, has become a kind of shorthand to mean "of or pertaining to the real Motor City." (Indeed, an insult rendered in Eminem's film 8 Mile is to be accused of being "810," i.e., poseur white trash from suburbs.) But have you ever wondered where the 313 area code came from?

In 1947, the people at AT&T saw a time when the seven-digit numbers of local exchanges would not be enough to handle the volume of business they hoped would be coming in the boom of postwar expansion. So they came up with something called the North American Numbering Plan (NANP for short) to divide the U.S. and Canada into smaller units. (The NANP now also includes parts of Mexico and the Caribbean.)

The first NANP cut up the long-distance telephone network into 87 areas. Back in the day, cutting-edge technology meant rotary-dial telephones. So for efficiency's sake, "dial pulls" were taken into consideration when handing out numbers. Dial pull measures the time it takes to pull the telephone dial around from a particular number to the stop lever, and for it to go back into position again before the next digit can be dialed. The higher the number, the longer the dial pull.

Area codes with the shortest dial pulls were given to the largest dialing areas in terms of existing and projected call volumes. The largest cities were given area codes with "1" as the middle digit, the number with the shortest dial pull. States that only had one area code were given a "0" as the middle digit.

In order, the most highly populated areas at the time, and thus the area codes with the shortest dial pulls, were New York City (the five boroughs only not the suburbs), 212; southern California from Los Angeles down to San Diego, 213; Chicago and environs, 312; and Detroit, including Port Huron and Ann Arbor, 313. The rest of the state of Michigan, including the Upper Peninsula, was 517. The 616 and 906 area codes, for western Lower and all of the Upper Peninsula, respectively, were put into service in the 1960s. Regions with the distinction of originally having "loser" area codes included Tennessee, 901; the Canadian Maritime Provinces of New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland, 902; and northern Kansas, 913.

Vince Carducci is a 313 refugee living in 212 territory.