This file contains vital information for more than 50 million deceased persons who had Social Security (SS) numbers and whose deaths were reported to the Social Security Administration. Most of the information is from 1962-2000, although the files include some data from as early as 1937. The files lists the person's name, SS number, birth date, state of residence where the SS number was issued, month and year of death, and place of residence at the time of death. The index is updated periodically and available for searching at several locations online, including http://rootsweb.com.
The SSDI is a particularly valuable resource for people with unusual surnames, as it will often help you track down distant cousins you never knew of before. By noting the places cited for the place of death and death benefits, and then calling information or searching online phone books for these areas, you have a reasonable chance of stumbling onto a descendant of a previously unknown sibling of your immigrant grandparent or great-grandparent. Even if you have a more common surname, you may be able to identify possible relatives by focusing your search on unusual first names that run in your family or a specific geographic region.
Using the information obtained from a search of this database, it is also possible to order a copy of the individual's application form. This is especially useful for people whose ancestors emigrated around the turn of the last century, as this form contains the name of the applicant's parents. To learn more about the SSDI in general, scan the articles accessible through Cyndi's List at http://www.CyndisList.com/socsec.htm.