There was a good Planet Money episode on how it got to be this way. [1] The SSN maybe originally was not meant to be used this way, but starting around 1943, go

There was a good Planet Money episode on how it got to be this way. [1] The SSN maybe originally was not meant to be used this way, but starting around 1943, government agencies were required to use it when possible. [2] That's less than a decade after the first SSN's were issued. 1. https://www.npr.org/sections/money/2018/03/14/593620579/episode-830-xxx-xx-xxxx https://www.npr.org/sections/money/2018/03/14/593620579/epis... 2. https://www.ssa.gov/foia/html/EO9397.htm https://www.ssa.gov/foia/html/EO9397.htm