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The logic behind the area code, at least at first

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To understand the reasoning for the current telephone area codes, it’s worth keeping in mind two things: The way that population levels differ from state to state, and the basic design of the early system.

The Numbering Plan Area, which Bell put into place starting in the 1940s, was designed to replace a far-more-complicated system that relied on operators to manually move calls through the system. The phone company wanted to make it possible for anyone to call anyone, anywhere, in an automated way.

Initially, this was sold as a boon for operators.

“In a few years long distance operators will be dialing calls, directly and unassisted, straight through to telephones as far away as the other side of the continent,” exclaimed a 1945 statement from Northwestern Bell published in the Minneapolis Morning Trbune.

The truth, of course, was that the goal was to remove operators from the equation entirely—because there would never be enough human operators to fill the inevitable need. Requiring human interaction just to dial a number from a certain distance away created artificial limits on how big the system could become.

But the question, of course, is how to organize that system. And that’s the part, from the outside, that doesn’t seem so clear—especially compared to other large, national apparatuses. The U.S. Interstate system, which has odd numbers going north and south, even numbers going east and west, and highway numbers that grow higher in value as you go further east or north, has a clear logic to it, even if it sometimes veers from this logic. Likewise, the first three digits in the U.S. ZIP Code system get higher the further west you go.

In comparison, area codes within the North American Numbering Plan don’t break down quite so neatly geographically. That’s because the real factor here wasn’t geography, but population need. As shown by this map, Bell appears to have based its initial decision-making on area codes on a combination of population and future need.

The real tell, in this sense, wasn’t the first number in the three-digit area code; it was the second. Initially, every area code installed had a second digit that was either a 0 or a 1. States with more than one area code generally had a 1 as a second digit (hence why New York City’s most common area code is 212), and states with a single area code generally had a zero in the second digit (hence why Florida has the 305 area code).

“A single [numbering plan area] for a state or province (Canada) is the most desirable arrangement from a customer dialing viewpoint,” explained Notes on Distance Dialing, a 1968 document by AT&T. “For this reason, the NPA boundaries were drawn coincident with existing state or provincial boundaries whenever it appeared that the ultimate central office code capacity for a single NPA would not be exceeded.”

This structure meant a couple of things: First, it was a bit of a godsend for people dialing on rotary phones, because it made the most valuable area codes the easiest to dial, making analog dials easier to push around when making a call.

This is highlighted in terms of who got the most popular codes. For example, California initially got the area codes 916, 415, and 213. L.A., of course, got the area code which required the fewest number of clicks on the analog dial. Chicago, likewise, got 312, Detroit 313, and Washington, D.C., 202. The largest and most prominent cities got the best codes, while smaller states had to drag the zero all the way around, almost as a punishment of sorts for not being bigger.

(And then there’s Manitoba, which got 204, a more efficient code than the Toronto area got, but I digress.)

But more importantly, it meant that the system was built with a degree of future-proofing. By leaving out numbers higher than 1 on the second digit, that meant that numerous area codes would be available in the decades to come, in case growth spurts hit and suddenly your state needs a lot of area codes—looking at you, Florida.
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    Updated 02-07-2020 at 06:31 PM by deriols