Area codes have been around since 1947. In the time before that, calling somebody on the phone long distance was a bit of a hassle. Callers would have to deal with operators who were having to tangle with switchboards, which made the press of even placing the call a hassle that could take a couple of minutes.

How Area Codes Came About

Area codes were first introduced in 1947 as part of the North American Numbering Plan (NANP), developed by AT&T and Bell Laboratories. This system was designed to simplify long-distance dialing across the U.S. and Canada. Each region was assigned a unique three-digit area code, with larger cities receiving codes with lower numbers to make dialing faster on rotary phones. The first direct-dial long-distance call using area codes was made in 1951, marking the start of a more efficient phone system.

How Area Codes Are Assigned

It may seem like the area codes that we used today, at least the numbers themselves, are completely random. However, there’s actually some logic behind how area codes were originally assigned, though it might seem random today. Here’s how it worked:

Early System

In the 1940s, when area codes were introduced under the North American Numbering Plan (NANP), two main factors guided the selection:

Number Patterns

The format used was NXX, where “N” could be any digit from 2 to 9, and “X” any digit from 0 to 9. This allowed for over 150 area codes. Numbers starting with 0 or 1 were often reserved for long-distance or special services, like toll-free lines.

Population Density

Cities with large populations, like New York (212), Los Angeles (213), and Chicago (312), received lower numbers because they were faster to dial on rotary phones, which were common then. Higher numbers, like 9 or 0, took longer to dial.

Modern Area Codes

As the demand for phone numbers grew due to population increases and mobile phones, many areas ran out of numbers, and new area codes were needed. Today, area codes are less dependent on population and more on the availability of numbers. “Overlays” (adding a new code to a region without splitting it) became common, making numbers less predictable.

However, the numbers are not chosen randomly—they still follow the NXX format, but the original logic of easier dialing or population-based assignments has largely faded.