I get to Plug a Gap in Cecil's knowledge!!! (Area codes)

[Northern_Piper]

I was browsing through my Return of the Straight Dope which I bought a while ago in my civic duty to keep this place afloat, and came across a column where Cecil admits to a lacuna in his knowledge, which I am in a position to fill! I’m so excited!

(Okay, so it’s a column about how they used to assign area codes, which is of mere historical relevance ever since the Great Area Code Divisions of the mid-90s, but I’m still excited.)

Cecil explains:

On the rotary-dial phones then in use, dialing a nine took a lot longer than dialing a one, which tied up expensive switching equipment. So AT&T assigned “low dial pull” numbers to the markets with the most telephones and thus presumably the highest number of incoming long-distance calls. New York got 212, Chicago 312, LA 213, Detroit 313, Dallas 214, and so on.

But he then goes on to add:

Some area codes aren’t so easy to explain. Boston got 617 while comparatively rural western Massachusetts got 413; Washington, D.C., got 202. (Zero, remember, has the highest dial-pull of all.) Whether these anomalies represented some smoldering vendetta against the eastern seaboard we may never know; the people responsible have long since retired.

I don’t have a cite for it, but the explanation I read long ago in a Canadian magazine that had a proto-Cecil answering column was that area codes with “1” as the middle digit meant that the state or province in question had two or more area codes, while state or provinces that had only one code for the entire area had codes with “0” as the middle digit.

This is consistent, of course, with Cecil’s explanation for why codes with “1” are normally assigned to heavily populated areas. Jurisidictions that are heavily populated will need more than one code. But the code also gives a bit more information: a code with a “1” was a sign that the code would not apply to the entire state/province. If a state or province had a city the size of Boston or Montreal, warranting its own code, the rest of the state or province would get a different code, with a “1”, to indicate that the area code will not apply to the entire state or province.

This explains why D.C. had a code with a “0” - since the same code applied to the entire District, it got a “0”, not a “1”, even though it was heavily populated. The anomaly wasn’t in the code, but in the fact that D.C. has the heaviest population density of any of the jurisdicitions.

[Exapno_Mapcase]

Confirmed here. All original 86 NPAs (area codes to you plebes), plus the smoking gun at the bottom of the page:

A simple pattern unified the original assignments of area codes in 1947. First, any state or province that had only a single area code (or shared an area code with an adjacent province) was assigned an area code with a 0 as the middle digit. All area codes in multi-code states and provinces were assigned with 1 as the middle digit. Since telephones in that day were rotary dial, consideration was also given to the number of “dial pulls” required for each area code; area codes with a small number of dial pulls were assigned to the largest cities and states. Thus, New York City, Los Angeles, and Chicago got 212, 213, and 312, while New Jersey, Washington DC, Maryland, and Connecticut got 201, 202, 301, and 203. There were some odd exceptions, though: Dallas, eastern Massachusetts, and Manitoba were all promoted above their importance in 1947, while Boston, Kansas City (both KS and MO), and the suburbs of New York City were demoted.