The Social Security Act of 1935 required the U. S. government to keep continuous records on the employment of 26 million individuals.
The first Social Security Numbers (SSNs) were issued by the Social Security Administration in November 1936 as part of the New Deal Social Security program.
"Within three months, 25 million numbers were issued.
"Before 1986, people often did not have a Social Security number until the age of about 14, since they were used for income tracking purposes, and those under that age seldom had substantial income. In 1986, American taxation law was altered so that individuals over 5 years old without Social Security numbers could not be successfully claimed as dependents on tax returns; by 1990 the threshold was lowered to 1 year old, and was later abolished altogether." (Wikipedia article on Social Security Number, accessed 01-17-2010).