Just so YOU know, SSI means Supplemental Security Income, just as I said. It does NOT mean Social Security in general. You stand corrected.
http://www.ssa.gov/ssi/
Actually I don't Social security is an Insurance program.
In the United States, Social Security refers to the Old-Age, Survivors, and Disability Insurance (OASDI) federal program.[1] The original Social Security Act (1935)[2] and the current version of the Act, as amended[3] encompass several social welfare and social insurance programs.
http://en.wikipedia.org/wiki/Social_Security_(United_States)
There is more if you care to read. SSI again is social security insurance if you would like a history lesson on when it started and the first person to collect it I can tell you all that if you like also.