Structure of Social Security Numbers last modified May 15, 2001 -------------------------------------------------------------------------------- A Social Security Number (SSN) consists of nine digits, commonly written as three fields separated by hyphens: AAA-GG-SSSS. The first three-digit field is called the "area number". The central, two-digit field is called the "group number". The final, four-digit field is called the "serial number". The process of assigning numbers has been changed at least twice. Until 1965, only half the group numbers were used. Before 1972, numbers were assigned by field offices; since 1972, they have all been assigned by the central office. The order in which numbers were assigned was changed in the 1972 transition. There may have been other changes, but it's difficult to get information on how things used to be done. -------------------------------------------------------------------------------- Area Numbers The area numbers are assigned to geographical locations. They were originally assigned the same way that zip codes were later assigned (in particular, area numbers increase from east to west across the continental US as do the ZIP codes). Most area numbers were assigned according to state (or territorial) boundaries, although the series 700-729 was assigned to railroad workers regardless of location (this series of area numbers was discontinued in 1964 and is no longer used for new SSNs). Area numbers assigned prior to 1972 are an indication of the SSA office which originally issued the SSN. Since 1972 the area number in SSNs corresponds to the residence address given by the applicant on the application for the SSN. In many regions the original range of area number assignments was eventually exhausted as population grew. The original area number assignments have been augmented as required. All of the original assignments were less than 585 (except for the 700-729 railroad worker series mentioned above). Area numbers of "000" have never been issued. The following table is now out of date. The SSA currently maintains an up-to-date version. I'm leaving the old one here in case the SSA's version goes away. As of 2001/5/15, the SSA lists group numbers as high as 768 as having been issued. 001-003 NH 400-407 KY 530 NV 004-007 ME 408-415 TN 531-539 WA 008-009 VT 416-424 AL 540-544 OR 010-034 MA 425-428 MS 545-573 CA 035-039 RI 429-432 AR 574 AK 040-049 CT 433-439 LA 575-576 HI 050-134 NY 440-448 OK 577-579 DC 135-158 NJ 449-467 TX 580 VI Virgin Islands 159-211 PA 468-477 MN 581-584 PR Puerto Rico 212-220 MD 478-485 IA 585 NM 221-222 DE 486-500 MO 586 PI Pacific Islands* 223-231 VA 501-502 ND 587-588 MS 232-236 WV 503-504 SD 589-595 FL 237-246 NC 505-508 NE 596-599 PR Puerto Rico 247-251 SC 509-515 KS 600-601 AZ 252-260 GA 516-517 MT 602-626 CA 261-267 FL 518-519 ID 627-645 TX 268-302 OH 520 WY 646-647 UT 303-317 IN 521-524 CO 648-649 NM 318-361 IL 525 NM *Guam, American Samoa, 362-386 MI 526-527 AZ Philippine Islands, 387-399 WI 528-529 UT Northern Mariana Islands 650-699 unassigned, for future use 700-728 Railroad workers through 1963, then discontinued 729-799 unassigned, for future use 800-999 not valid SSNs. Some sources have claimed that numbers above 900 were used when some state programs were converted to federal control, but current SSA documents claim no numbers above 799 have ever been used. As of Feb 10, 1999 the most recent area numbers to have been assigned include 650-658, 667-675, and 680. This list is from the SSA's web site, which shows the highest group number assigned for each area. -------------------------------------------------------------------------------- NEW SSN LISTING: The chart below shows the first 3 digits of the social security numbers assigned throughout the United States and its possessions. See "Note" at bottom of page. 001-003 New Hampshire 004-007 Maine 008-009 Vermont 010-034 Massachusetts 035-039 Rhode Island 040-049 Connecticut 050-134 New York 135-158 New Jersey 159-211 Pennsylvania 212-220 Maryland 221-222 Delaware 223-231 Virginia 691-699* 232-236 West Virginia 232 North Carolina 237-246 681-690 247-251 South Carolina 654-658 252-260 Georgia 667-675 261-267 Florida 589-595 766-772 268-302 Ohio 303-317 Indiana 318-361 Illinois 362-386 Michigan 387-399 Wisconsin 400-407 Kentucky 408-415 Tennessee 756-763* 416-424 Alabama 425-428 Mississippi 587-588 752-755* 429-432 Arkansas 676-679 433-439 Louisiana 659-665 440-448 Oklahoma 449-467 Texas 627-645 468-477 Minnesota 478-485 Iowa 486-500 Missouri 501-502 North Dakota 503-504 South Dakota 505-508 Nebraska 509-515 Kansas 516-517 Montana 518-519 Idaho 520 Wyoming 521-524 Colorado 650-653 525,585 New Mexico 648-649 526-527 Arizona 600-601 764-765 528-529 Utah 646-647 530 Nevada 680 531-539 Washington 540-544 Oregon 545-573 California 602-626 574 Alaska 575-576 Hawaii 750-751* 577-579 District of Columbia 580 Virgin Islands 580-584 Puerto Rico 596-599 586 Guam 586 American Samoa 586 Philippine Islands 700-728 Railroad Board** 729-733 Enumeration at Entry NOTE: The same area, when shown more than once, means that certain numbers have been transferred from one State to another, or that an area has been divided for use among certain geographic locations. Any number beginning with 000 will NEVER be a valid SSN. The information in our records about an individual is confidential by law and cannot be disclosed except in certain very restricted cases permitted by regulations. * = New areas allocated, but not yet issued ** 700-728 Issuance of these numbers to railroad employees was discontinued July 1, 1963. -------------------------------------------------------------------------------- Group Numbers The group number is not related to geography but rather to the order in which SSNs are issued for a particular area. Before 1965, only half the group numbers were used: odd numbers were used below 10 and even numbers were used above 9. In 1965 the system was changed so assignments continued with the low even numbers and the high odd numbers. So, group numbers for each area number are assigned in the following order: Odd numbers, 01 to 09 Even numbers, 10 to 98 Even numbers, 02 to 08 Odd numbers, 11 to 99 Group codes of "00" aren't assigned In each region, all possible area numbers are assigned with each group number before using the next group number. This means the group numbers can be used to find a chronological ordering of SSNs within a region. When new group numbers are assigned to a state, the old numbers are usually used up first. SSA publishes a list every month of the highest group assigned for each SSN Area. For example, if the highest group assigned for area 999 is 72, then we know that the number 999-04-1234 is an invalid number because even Groups under 9 have not yet been assigned. -------------------------------------------------------------------------------- Serial Numbers Serial numbers are assigned in chronological order 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. -------------------------------------------------------------------------------- Invalid SSNs Any SSN conforming to one of the following criteria is an invalid number: Any field all zeroes (no field of zeroes is ever assigned). First three digits above 770 A pamphlet entitled "The Social Security Number" (Pub. No. 05-10633) provides an explanation of the SSN's structure and the method of assigning and validating Social Security numbers. This description of the structure of the Social Security Number is based on messages written by Jerry Crow and Barbara Bennett. The information has been verified by its correspondence to the SSA's Program Operations Manual System (POMS) Part 01, Chapter 001, subchapter 01, which can be found at Federal Depository Libraries. (SSA Pub. No. 68-0100201.) -------------------------------------------------------------------------------- Brought to you by FinalHope Source: http://www.cpsr.org/cpsr/privacy/ssn/ssn.structure.html _________________________________________________________________ Add MSN 8 Internet Software to your existing Internet access and enjoy patented spam protection and more. Sign up now! http://join.msn.com/?page=dept/byoa