Beginning June 25, 2011, the Social Security Administration introduced randomization into the assignment of Social Security numbers (SSNs).
Prior to June, 2011, Social Security numbers generally were assigned on a state-by-state basis. For example, Texas residents were given SSNs with the first three numbers in the range of 449-467.
However, to help prevent identity theft and provide numbering flexibility, SSNs are now assigned on a random basis to new SSN recipients. Current SSN holders will not have their number affected by the new random system.
You can learn more about how "legacy" SSNs were assigned on the basis of state by visiting here :
https://secure.ssa.gov/poms.nsf/0/b5743fd0e02b42578525754c0005a686