What Social Security numbers mean
Everyone who has a Social Security number has one that’s formatted the same. It’s three sets of numbers: The first has three digits, the second has two digits, and the third has four digits. There’s been a lot of speculation over the years about what these numbers represent, but it’s actually pretty simple. Here’s what those numbers stand for.
Area number
The area number is the first three digits of your Social Security number. Before 2011, this number generally corresponded to your zip code at the time of the application. From 1936 to 1972, Social Security numbers were issued from local offices, and anyone could apply at any office. In that period, the number simply represented the office you applied through. But the process was centralized in 1972, so all new Social Security numbers were issued based on your mailing address.
Before 2011, the area number could range from 001 to 772, though some numbers were reserved for special uses. The further west you went, the higher the number became. After 2011, Social Security numbers became randomly assigned, so they no longer correspond to a person’s mailing address or physical location.
Group number
The group number is the middle two digits of a Social Security number. These were issued in a more seemingly haphazard way but still had a particular pattern. Odd numbers from 01 to 09 were issued first in any given area, then even numbers from 10 through 98. Next were even numbers from 02 to 08, and last were odd numbers from 11 through 99.
This division was strictly for administrative purposes and didn't really correspond to anything. It was more of a way of randomizing Social Security numbers before the advent of modern computing. There are myths that these numbers contained detailed coded information about race, but that has been debunked.
Serial number
The last four digits are the serial number. They originally ran consecutively from 0001 through 9999. So, if you lived next door to someone who applied for a Social Security number directly after you, it would be possible for the two of you to have Social Security numbers that are only one digit apart.
Modern methods of randomization have made it harder to guess Social Security numbers for deceased people or children, which people have used in the past to try to change their identity or to obtain credit under a false name. Modern tracking systems have also made this much more difficult.
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