In 1947, AT&T came up with its now-familiar (and -expanded) list of 86 three-digit area codes for the North American telephone system. For example, 504 was assigned to Louisiana, 306 to Saskatchewan, 715 to northern Wisconsin, and so on. I know that there are certain restrictions placed on which numbers can appear in which position, but within these general rules, how did they decide which geographical region got assigned which area code? I can see that the middle digit is always 1 if the area code covers only part of a state or province, and 0 otherwise, but apart from that I’m not spotting any obvious patterns. The codes don’t appear to be assigned in alphabetical or geographic order. And when a state or province has multiple area codes, they don’t appear to have any relationship to one another. For example, New York has 212, 315, 518, 716, and 914. Why not 212, 213, 214, 215, and 216?
Yes, that’s a very good article, but unfortunately not in the sense of “answers my question”.
Note: fixed coding in OP.
From Area Code History:
From Telephone numbering plan:
That’s the answer. You couldn’t start billing until the call was connected, so the phone companies wanted the most populous cities to have the lowest numbers (less time dialing.)
Tone dialing obviously made that requirement moot.
I’ve heard it said that the “212” for New York City was to match the rapid pace of life there, busy New Yorkers can’t be expected to waste a lot of time dialing 8s or 9s on rotary phones. But I think this is largely a just-so story.
If you were in New York, you wouldn’t be dialing New York’s area code.
It’s the opposite, more calls were going into New York City than other places and 212 had the shortest pulse code (the pulse code for 0 was ten pulses) and 1 could not be the first to last digit of an area code.
I believe this is probably true and not a story as the next two shortest pulse codes 213 and 312 were assigned to the next two biggest cities of LA and Chicago.
This was to reduce pulse code traffic on the lines.
The only “customized” area code in the USA is the one for the Space Coast near Cape Kennedy, FL … 321 … like the countdown for the rockets … {Cite} …
Now ten digit dialing, free long distance, and cell phones are making area codes meaningless. I don’t know anyone who changes their cell phone number anymore when they move - I sure as hell won’t give up the number I have had for almost 18 years just because I moved across the country.
That, plus the fact that the electromechanical switches (aka selectors) that were used at the time to connect the caller to the designated callee number were expensive and a scarce resource. Whenever a call was made, the caller’s line would be linked to an available switch, which would establish the connection. You’d want that connection to be established as fast as possible to make the switch available for the next dialler (the switch would not remain busy throughout the call, it would become available once the connection was set up).
There is a scene in Hitchcock’s Dial M For Murder that immortalised the operation of electromechanical Strowger switches in telephone exchanges.
So, to sum up:
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Area codes with a “1” in the center were assigned to avoid two numbers close numerically from being close geographically. (note that this was not true of the “0” codes, as for example Maryland and Delaware, which are next door neighbors both numerically and geographically).
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Area codes were assigned so that lower numbers were assigned to more-populated areas.
Notice that, of the “0” codes, none has a total sum of the non-zero digits in excess of 11. I suspect this was to avoid the possibility of something like 909, which would have the maximum number of clicks available under the scheme.
Not sure what you mean by that. Alaska is 907, for example, for a total of 26 pulses.
He was referring to the original 86 area codes linked in the OP. None of them go past 21 pulses total.
Paxx has already listed what I think were the only two criteria behind the original assignments: short dialpulls for the biggest cities, and similar codes should not be adjacent. It was a bit of a surprise to us area code nerds when in 1993 North Carolina was given 910*—right next to 919.
*910 had originally been assigned to TWX numbers in the Western US.