Area Number

The Area Number is assigned by the geographical region. Prior to 1972, cards were issued in local Social Security offices around the country and the Area Number represented the State in which the card was issued. This did not necessarily have to be the State where the applicant lived, since a person could apply for their card in any Social Security office. Since 1972, when SSA began assigning SSNs and issuing cards centrally from Baltimore, the area number assigned has been based on the ZIP code in the mailing address provided on the application for the original Social Security card. The applicant's mailing address does not have to be the same as their place of residence. Thus, the Area Number does not necessarily represent the State of residence of the applicant, either prior to 1972 or since.

Generally, numbers were assigned beginning in the northeast and moving westward. So people on the east coast have the lowest numbers and those on the west coast have the highest numbers.

Note. One should not make too much of the "geographical code." It is not meant to be any kind of useable geographical information. The numbering scheme was designed in 1936 (before computers) to make it easier for SSA to store the applications in Social Security Administration files in Baltimore since the files were organized by regions as well as alphabetically. It was really just a bookkeeping device for Social Security Administration internal use and was never intended to be anything more than that.

See Complete list of the SSN Number Allocations by State.

Group Number

Within each area, the group number (middle two (2) digits) range from 01 to 99 but are not assigned in consecutive order. For administrative reasons, group numbers issued first consist of the ODD numbers from 01 through 09 and then EVEN numbers from 10 through 98, within each area number allocated to a State. After all numbers in group 98 of a particular area have been issued, the EVEN Groups 02 through 08 are used, followed by ODD Groups 11 through 99.

1. ODD, 01 to 09 (01, 03, ... 09)
2. EVEN, 10 to 98 (10, 12, ... 98)
3. EVEN, 02 to 08 (02, 04, ... 08)
4. ODD, 11 to 99 (11, 13, ... 99)

Check the latest Social Security Number Monthly Issuance Table at SSA's Website for the highest group number assigned for each SSN Area. For example, if the highest group number assigned for area 999 is 72 (within the EVEN, 10 to 98 range), then we know that alleged number 999-04-1234 is an invalid number because group number in the EVEN, 02 to 08 range have not yet been assigned.

Group Number Myth

As should be clear from the explanation of the SSN numbering scheme, the "group number" refers only to the numerical groups 01-99. For filing purposes, the "area numbers" are broken down into these numerical subgroups. So, for example, for area numbers starting with 527 there would be 98 subgroups, one for every number starting with 527-01, and one for every number starting with 527-02, and so on. This was done back in 1936 because in that era there were no computers and all the records were stored in filing cabinets. The early program administrators needed some way to organize the filing cabinets into sub-groups, to make them more manageable, and this is the scheme they came up with.

Serial Number

Serial numbers (last four (4) digits) are assigned consecutively from 0001 through 9999 within each area and group number as the applications are processed. Serial number "0000" is never used. Before 1965, when number assignment was transferred from field offices to the central office, serial numbers may have been assigned in a strange order. (Some sources claim that 2000 and 7000 series numbers were assigned out of order. That no longer seems to be the case.) Currently, the serial numbers are assigned in strictly increasing order with each area and group combination.

See which SSN numbers are Invalid or Impossible.