Social Security Numbers are created and distributed by the Social Security Administration according to specific guidelines. Each of the three parts is numbered according to a specific scheme.
Area Number Defined
The first three numbers constitute the Area Number and are determined by geographical region. The Area Number is based on where the Social Security application was submitted and may not correspond to the place of residence of the applicant.
Area Number Identified
Area Numbers were allocated starting in New England and generally increased going westward. Therefore, people applying for Social Security Numbers on the East Coast generally have a lower Area Number than those applying in the Plains or the West Coast.
Group Number Defined
The Group Number is comprised of the middle two digits in the Social Security Number. These can range from any number from 01 to 99.
Group Number Assignment
Group Numbers are assigned in each area using a special order developed by the Social Security Administration. First assigned are odd numbers 01 to 09 followed by even numbers 10 to 98. After all of these numbers have been used, even numbers 02 to 08 are used followed by odd numbers 11 to 99.
Serial Number Defined and Assigned
The last four digits of a Social Security Number are called the Serial Number. These are simply assigned in consecutive order from 0001 to 9999.