For most young people today, having a Social Security number (and its accompanying identification card) is normal. Since parents wishing to claim their dependent children for tax deduction purposes were required to obtain Social Security cards for each child starting about 1986, many of those young people don’t remember ever not having a number.
When the government’s Social Security program was first instituted in late 1935, the intent was for the issuing agency (the Social Security Administration, SSA) to track lifetime wages for individual citizens in order to calculate eventual retirement benefits. Few people in those early days understood the program. For example, when a leather company inserted a sample SSA card in the wallets they sold, as many as 40,000 people adopted the “specimen” number as their own!
Over the years, the SSA number has taken on greater significance. Though the actual card warned “Not For Identification,” this caution was mostly ignored (and has been removed from the newer generation of cards). See the card above for an early, notable example.