Social Security Numbers

Social Security Numbers

Ever wonder how they "invent" this seemingly random series of numbers called our Social Security number? Wonder no more! A Social Security number or SSN is composed of 3 parts called the Area, Group and Serial.


For the most part (there are exceptions), the Area is determined by where the individual applied for their SSN (before 1972) or resided at the time of their application (after 1972). The Areas are assigned as follows:

001-003New Hampshire (NH)
004-007Maine (ME)
008-009Vermont (VT)
010-034Massachussetts (MA)
035-039Rhode Island (RI)
040-049Connecticut (CT)
050-134New York (NY)
135-158New Jersey (NJ)
159-211Pennsylvania (PA)
212-220Maryland (MD)
221-222Delware (DE)
223-231Virginia (VA)
232-236West Virginia (WV)
237-246North Carolina (NC)
247-251South Carolina (SC)
252-260Georgia (GA)
261-267Florida (FL)
268-302Ohio (OH)
303-317Indiana (IN)
318-361Illinois (IL)
362-386Michigan (MI)
387-399Wisconsin (WI)
400-407Kentucky (KY)
408-415Tennessee (TN)
416-424Alabama (AL)
425-428Mississippi (MS)
429-432Arkansas (AR)
433-439Louisianna (LA)
440-448Oklahoma (OK)
449-467Texas (TX)
468-477Minnesota (MN)
478-485Iowa (IA)
486-500Missouri (MO)
501-502North Dakota (ND)
503-504South Dakota (SD)
505-508Nebraska (NE)
509-515Kansas (KS)
516-517Montana (MT)
518-519Idaho (ID)
American Samoa
520Wyoming (WY)
Northern Mariana Islands
521-524Colorado (CO)
Philippine Islands
525Mew Mexico (NM)
526-527Arizona (AZ)
528-529Utah (UT)
530Nevada (NV)
531-539Washington (WA)
540-544Oregon (OR)
545-573California (CA)
574Alaska (AK)
575-576Hawaii (HI)
577-579Washington, District of Columbia (DC)
580Virgin Islands (VI)
581-584Puerto Rico (PR)
585New Mexico (NM)
586Pacific Islands
587-588Mississippi (MS)
589-595Florida (FL)
596-599Puerto Rico (PR)
600-601Arizona (AZ)
602-626California (CA)
627-699Unassigned - Future Use
700-728Railroad Workers through 1963
729-899Unassigned - Future Use
900-999Not Valid (1)

(1) Were used for program purposes when state aid to the aged, blind and disabled was converted to a federal program administered by SSA.

As the Areas asigned to a locality are exhausted, new areas form the pool are assigned. This is why some states have non-contiguous groups of Areas.


The Group portion of the SSN has no meaning other than to determine whether or not a number has been assigned. SSA publishes a list every month of the highest group assigned for each SSN Area. The order of assignment for the Groups is: Odd numbers under 10, even numbers over 9, even numbers under 9 except for 00 which is never used, and odd numbers over 10. For example, if the highest group assigned for area 999 is 12, then we know that the number 999-04-1234 is an invalid number because even groups under 9 have not yet been assigned.


The Serial portion of the SSN has no meaning. The Serial is not assigned in strictly numerical order. The Serial 0000 is never assigned.

Card Distribution

Before 1973, Social Security Cards with pre-printed numbers were issued to each local SSA office. The numbers were assigned by the local office. In 1973, SSN assignment was automated and outstanding sotcks of pre-printed cards were destroyed. All SSNs are now assigned by computer from headquarters. There are rare cases in which the computer system can be forced to accept a manual assignment such as a person refusing a number with 666 in it.

A pamphlet entitled "The Social Security Number" (Pub. No. 05-10633) proveds an explanation of the SSN's structure and the method of assigning and validating Social Security numbers.

This information was taken (with small word choice modifications) from the "Social Security Administration & Genealogy FAQ (v.7/2001)" found at Yigal Rechtman's Homepage, Section Q.1.4. This passage was copied in it's entirety because this information keeps moving around the internet, and I wanted to be able to find it quickly.