Social Security Number

The Social Security Number (SSN) was created in 1936 as a means of tracking workers’ earnings and eligibility for Social Security benefits. SSNs are issued to most U.S. citizens, and to some non-citizens lawfully admitted to the United States. Through a process known as enumeration, a unique nine-digit number is created. The number is divided into three parts &mdash; first three digits represent the geographic area where the SSN was assigned; the middle two are the group number, which is assigned in a specified order for each area number; and the last four are serial numbers ranging from 0001 to 9999. Because of the number’s uniqueness and broad applicability, SSNs have become the identifier of choice for government agencies and private businesses, and are used for a myriad of non–Social Security purposes.