The Social Security Death Index (SSDI) is a database of over 77 million people who have been reported as having died. Included in the database are about 400 thousand railroad retirement records from early 1900s to 1950s. The social security administration has organized the social security numbers into three parts: the first three digits designate area, the second two digits designate group, and the final four digits designate the serial number. The area numbers are assigned to a region. Prior to 1972 it was the state in which the card was issued. These social security state codes are listed on page 3-4 of Rootsweb Guide Lesson Number 10 - Social Security Death Index The SSDI provides information as to where the last benefits were sent, this can be often confused with where the person died.
I found the SSDI listed on three major web sites: Ancestry.com, Rootsweb.com, and genealogyinc.com. Ancestry.com requires a fee to use the index, genealogyinc.com seems to be a satellite of Ancestry.com, and Rootsweb.com has a very limited search tool, although they do provide a pre-typed letter to send to the SSA. I use familysearch.org which is part of the LDS church and provides the greatest latitude for searches which include the SSDI and is free. There is also a free link to the SSDI at http://genealogy.about.com/od/vital_records/a/ssdi.htm
The index itself has the following information: first and last names, the birth and death date, the social security number and the state in which the social security number was issued. Any one of these pieces of information can be used to search for your ancestor. But do not be surprised if on your first attempt at searching the data base, your ancestor does not appear. This is commonly due to the fact of how your ancestor was entered into the database. Most of the time, the names entered are their proper legal names, not what the relatives often referred to him as. Some times there is a discrepancy in birth and death dates. This is often due to typos but also due to relatives who submit information who don't really know the correct spelling or actual date when Uncle Bob died.
Of course not everyone is listed on the SSDI, even though they applied for social security. If the funeral home or a relative did not report the death, Uncle Bob would not be on the list and if Uncle Bob is not dead yet, he would not be on the list. Odd as that may seem, sometimes I check the SSDI from time to time to verify if a relative has passed on.
The state in which your relative signed up for social security can often be surprising. Uncle Bob was born in Indiana, died in Washington, but one summer he worked in Colorado and that was where he submitted for a social security card.
Once you have found Uncle Bob on the SSDI you can acquire further information about him by requesting a copy of his SS-5 form or sending a letter to the Social Security Administration with a fee. The SSA charges $27 dollars for each request with the social security number or $29 if the number is unknown. It can be quite expensive if such a search is done for each member of your family tree. You can obtain an SS-5 form at the Social Security Administration which is at http://www.ssa.gov/foia/html/foia_guide.htm but also SSA notes that you do not need to use the form and can address a request to: Social Security Administration, OEO FOIA Workgroup, 300 N. Green Street, P.O. Box 33022, Baltimore, Maryland 21290-3022.
FOIA stands for the Freedom of Information Act. In order to apply for social security, Uncle Bob had to fill out an SS-5 form. This form in addition to the SSDI index has information concerning his full name including the name given to him at birth and any possible maiden name (for women), his present mailing address, place of birth, fathers and mother's full names, his race, and his current employer's name and address.
You can see the information provided on such a form can be quite valuable and expand what you knew about dear old Uncle Bob. The Social Security database is just another tool that can be used in finding information on your ancestors. I hope the information I collected will help you navigate around the pitfalls of our information age.