Social Security Online | FOIA SSN's by State

What can you tell from a Social Security Number? The first 3 digits of a person's social security number are determined by the zip code of the mailing address shown on their application.

How is this useful? It provides a piece of their address history and can help identify one individual from others with the same name.

One exception - if the number begins with 700 to 728 it was issued prior to 1963 and to someone who worked for the railroad when the application was filed.