The original need arose for the SSN because Social Security benefits are dependent on Social Security contributions. This required the Social Security Administration to track every individual's earnings without ambiguity by assigning them a unique identifier, but the number was never intended to be a universal identifier. Because identification by name and birthdate is non-unique, however, information-gathering organizations at the beginning of the welfare state wanted a unique identifier but didn't want to spend money creating their own. Social Security Numbers filled the need, their usage spreading to government agencies unrelated to the SSA, libraries, schools, and hospitals.
The Internal Revenue Service tried to issue their own identifier in 1961, but they were told to use the SSN because their identification system would be too expensive.
Authorized Uses of Social Security Numbers
Source: Database Nation: The Death of Privacy in the 21st Century. Simson Garfinkel
1943 Federal agencies use SSN exclusively for employees.
1961 Civil Service Commission uses SSN as an employee identifier.
1962 Internal Revenue Service uses SSN as taxpayer identification.
1969 Department of Defense uses SSN as an Armed Forces identifier.
1972 U.S. begins issuing SSNs to anyone receiving or applying for federal benefits.
1975 AFDC (Aid for Families with Dependent Children) uses SSN for eligibility.
1976 States use SSN for tax and general public assistance identification and for driver's licenses.
1977 Food stamp program uses SSN for household member eligibility.
1981 School lunch program uses SSN for adult household member eligibility.
1981 Selective Service System uses SSN for draft registrants.
1982 Federal loan program uses SSN for applicants.
1983 SSN required for all holders of interest-bearing accounts.
1984 States authorized to require SSN for AFDC, Medicaid, unemployment compensation, food stamp programs, and state programs established under a plan approved under Title I, X, XIV, or XVI of the Social Security Act.
1986 SSN may be used as proof of employment eligibility.
1986 SSN required for taxpayer identification for tax dependents age five and over (effective for 1988 returns).
1986 Secretary of Transportation authorizes use of SSN for commercial motor vehicle operator's licenses.
1988 SSN required for taxpayer identification for tax dependents age two and over (effective for 1990 returns).
1988 States use parents' SSNs to issue birth certificates.
1988 States and/or blood donation facilities use SSN for blood donor identification.
1988 All Title II beneficiaries required to have SSN for eligibility.
1989 National Student Loan Data System includes SSN of borrowers.
1990 SSN required for taxpayer identification for tax dependents age one and over (effective for 1991 returns).
1990 SSN required for eligibility for all Department of Veterans Affairs payments.
1990 SSN required for officers of food and retail stores that redeem food stamps.
1994 Use of SSN authorized for jury selection.
1994 Use of SSN authorized by Department of Labor for claim identification numbers for worker's compensation claims.
1994 SSN required for taxpayer identification for tax dependents regardless of age (effective for 1996 returns).
1996 SSN required for any applicant for a professional license, commercial driver's license, occupational license, or marriage license (must be recorded on the application). The SSN of any person subject to a divorce decree, support order, or paternity determination or acknowledgment would have to be placed in the pertinent records. SSNs are required on death certificates.
1996 The Attorney General authorized to require any noncitizen to provide his or her SSN for inclusion in Immigration and Naturalization Service (INS) records.
1996 Driver's licenses required to display an SSN.
| 
