Voter ID laws have been a topic of heated political debate during the Trump administration, but proposals for a national identification card have been largely absent from this discussion. The United States is peculiar in the sense that it has resisted the implementation of a national ID system; the closest in this regard would be the American passport, which not many individuals obtain for various reasons.
In light of a lack of a national ID card system, the Social Security Number has been used for decades as a go-to form of identification for quite a few purposes. Your SSN is part of your credit history, employment record and even criminal background profile. The Federal Bureau of Investigation treats the SSN as a criminal record number, and this is despite warnings by the Social Security Administration to not use this number for purposes other than accessing benefits. The Internal Revenue Service also uses the SSN as an individual taxpayer identification number, although foreigners and self-employed professionals can obtain separate ITINs to conduct business and report income.
The widespread use of the SSN in the U.S. makes it possible to locate people in some cases. The first step of the process is to validate the SSN through the online system maintained by the Social Security Administration at www.ssa.gov/employer/ssnv.htm. It is important to keep in mind that the use of this system requires registration and it is intended for employers who wish to verify their new hires. Part of the SSN structure is considered to be public information; this allows some websites to offer limited online validation tools.
Since SSNs are used by many private and public entities, they often end up being included in records managed by information brokers, particularly by credit reporting bureaus. Private investigators often subscribe to databases that match SSNs to public records; this combination of information sources can be used to locate individuals. Your best bet is to provide private investigators with as much information about the person as possible because the SSN by itself may not yield accurate results.
Ancestry websites that compile vital statistics reported to the SSA manage databases with records of deceased individuals. If you suspect that the person you are looking for is no longer with us, you can use the SSN to search these databases and find the burial or internment site. If the person you are trying to find owes child support, you should contact your local enforcement agency; in this case, you may not even need to provide the SSN in question.