The social security number is divided into three groups, the area number, which represents the first three digits, the group number, and the serial number. The first five digits of someone's number can be guessed (some states are easier then others, less populated states are easier to guess), however, the last four digits cannot. Applicants from the same state, and around the same age can easily share the first five digits of the social security number, especially if the applicant applies in a less populated state (Wyoming, Alaska, Montana, the Dakotas, to name a few). The area number reflects the state in which the person applied. Before 1972, the area number merely reflected the location of the social security office in which the person applied (a person who lives in Colorado goes on vacation to Texas. That person decides to apply for a social security number in an office in Texas. Although that person lives in Colorado, that person will receive a Texas number). After 1972, the area number reflects the location of the mailing address of the applicant. The zip code determines the area number (If a person applies for a number, using zip code 32611, which is in Florida, that person will receive a Florida social security number). Additionally, the area numbers within a state are assigned in numerical order within a group (the middle two digits). (The first area-group combination that was assigned in Iowa was 478-01, followed by 479-01, then 480-01, 481-01, 482-01, 483-01, 484-01, 485-01, then 478-03, 479-03.....).

The middle two digits, which are also known as the group number reflect when a person received a number. For each state, the group numbers assigned are different. The group numbers are not assigned in numerical order. All odd numbers below 10 are assigned first (01, 03, 05....), then all even numbers 10 and above are assigned (10, 12, 14.....98), then all even numbers below 10 are assigned (02, 04, 06, 08), then all odd numbers above 10 are assigned (11, 13, 15....99). People, who are the same age will likely have the same middle two digits (or similar) within a state. However, all states are different, (someone who received an Ohio number in 1990 will likely have the group number "92", someone who received a Pennsylvania number in 1990 will likely have a group number of "72", and someone in North Carolina in 1990 will likely have a group number of "67" or "69". Before 1965, only half of the group numbers (low odd numbers, and high even numbers) were used, which required a few states to add an extra area number (Mississippi had to add 587, and New Mexico added 585). In 1965, the low evens, and high odd group numbers were allowed. Also, the middle two digits can determine whether that number is valid. On the SSA website, high groups are displayed for every area number. The high group means that the group was the latest group that has been assigned. For example, if the high group of an area number was 92, then a social security number with the group number of 04 would not be valid, because 04 in that group number had not been assigned yet.

Also, some states exhausted their original number assignments, which required a new series of numbers for that state, which is why some states have a non-continuous set of area numbers (Arizona was the first state to exhaust their original assignment. They were assigned 526-527. After the area-group combinations of 526-99 and 527-99 were assigned, new numbers had to be assigned. Therefore, the SSA assigned area numbers 600-601 to Arizona). Every social security number assigned before March of 1983 began with a "5", or below.

Also, the area number "000" will not be assigned, and is not valid. Also "666" is not valid either. However, 111 (New York), 222 (Delaware), 333 (Illinois), 444 (Oklahoma), and 555 (California) are all valid area numbers. As of 2009, no area numbers are above "772". Also, area numbers between 734-749 are not valid numbers. California will likely exhaust it's current series of 602-626 in 2013, which will lead to an additional series of numbers being assigned. The group number "00" is also not valid, and the serial number "0000" is not valid.

The assignments are as follows (also written are the period of time issued, and high group number as of April 2009. If a social security number is presented outside of the high group, it is invalid! For example 001-15-xxxx is invalid, since 08 is the latest group number issued).

001-003 New Hampshire (1936-present) High Group: 08 for 001, 06 for 002-003
004-007 Maine (1936-present) High Group: 11 for 004-005, 08 for 006-007
008-009 Vermont (1936-present) High Group: 92
010-034 Massachusetts (1936-present) High Group: 92 for 010-021, 90 for 022-034
035-039 Rhode Island (1936-present) High Group: 74 for 035, 72 for 036-039
040-049 Connecticut (1936-present) High Group: 13 for 040-047, 11 for 048-049
050-134 New York (1936-present) High Group: 98 for 050-094, 96 for 095-134
135-158 New Jersey (1936-present) High Group: 21 for 135-148, 19 for 149-158
159-211 Pennsylvania (1936-present) High Group: 84 for 159-208, 82 for 209-211
212-220 Maryland (1936-present) High Group: 83
221-222 Delaware (1936-present) High Group: 08
223-231 Virginia (1936-November 2004) High Group:99 (exhausted)
691-699 Virginia (November 2004-present) High Group: 12 for 691-692, 10 for 693-699
232 West Virginia and North Carolina (but now West Virginia, 1936-present) High Group:55
233-236 West Virginia (1936-present) High Group: 55 for 233-235, 53 for 236
237-246 North Carolina (1936-October 2002) High Group: 99 (exhausted)
681-690 North Carolina (October 2002-present) High Group: 18 for 681-685, 16 for 686-690
247-251 South Carolina (1936-November 1996) High Group: 99 (exhausted)
654-658 South Carolina (November 1996-present) High Group: 32 for 654, 30 for 655-658
252-260 Georgia (1936-October 1997) High Group: 99 (exhausted)
667-675 Georgia (October 1997-present) High Group: 40
261-267 Florida (1936-September 1980) High Group: 99 (exhausted)
589-595 Florida (September 1980-March 2001) High Group: 99 (exhausted)
766-772 Florida (March 2001-present) High Group 80 for 766-770, 78 for 771-772
268-302 Ohio (1936 present) High Group: 15 for 268-277, 13 for 278-302
303-317 Indiana (1936-present) High Group: 35 for 303-304, 33 for 305-317
318-361 Illinois (1936-present) High Group: 08 for 318-341, 06 for 342-361
362-386 Michigan (1936-present) High Group: 37 for 362-363, 35 for 364-386
387-399 Wisconsin (1936-present) High Group: 31 for 387-393, 29 for 394-399
400-407 Kentucky (1936-present) High Group: 71 for 400-401, 69 for 402-407
408-415 Tennessee (1936-July 2005) High Group: 99 (exhausted)
756-763 Tennessee (July 2005-present) High Group: 09 for 756-759, 07 for 760-763
416-424 Alabama (1936-present) High Group: 65 for 416-418, 63 for 419-424
425-428 Mississippi (1936-October 2006): High Group 99 (exhausted)
587 Mississippi (1964-December 2006): High Group 99 (exhausted)
588 Mississippi (December 2006-present) High Group: 05
752-755 Mississippi (February 2007-present) High Group: 03
429-432 Arkansas (1936-January 2001) High Group: 99 (exhausted)
676-679 Arkansas (January 2001-present) High Group: 18 for 676, 16 for 677-679
433-439 Louisiana (1936-October 1999) High Group: 99 (exhausted)
659-665 Louisiana (October 1999-present) High Group: 18
440-448 Oklahoma (1936-present) High Group: 25 for 440-446, 23 for 447-448
449-467 Texas (1936-August 1988) High Group: 99 (exhausted)
627-645 Texas (August 1988-present) High Group:19 for 627-641, 17 for 642-645
468-477 Minnesota (1936-present) High Group: 53 for 468-473, 51 for 474-477
478-485 Iowa (1936-present) High Group:39 for 478-484, 37 for 485
486-500 Missouri (1936-present) High Group: 27 for 486-495, 25 for 496-500
501-502 North Dakota (1936-present) High Group: 35 for 501, 33 for 502
503-504 South Dakota (1936-present) High Group: 43 for 503, 41 for 504
505-508 Nebraska (1936-present) High Group: 55 for 505-506, 53 for 507-508
509-515 Kansas (1936-present) High Group: 29 for 509-515
516-517 Montana (1936-present) High Group: 47 for 516, 45 for 517
518-519 Idaho (1936-present) High Group: 83 for 518, 81 for 519
520 Wyoming (1936-present) High Group: 57
521-524 Colorado (1936-June 1996) High Group: 99 (exhausted)
650-653 Colorado (June 1996-present) High Group: 54 for 650, 52 for 651-653
525 New Mexico (1936-June 1993) High Group: 99 (exhausted)
585 New Mexico (1959-September 1993) High Group: 99 (exhausted)
648-649 New Mexico (September 1993-present) High Group: 50
526-527 Arizona (1936-March 1983) High Group: 99 (exhausted)
600-601 Arizona (March 1983-July 2000) High Group: 99 (exhausted)
764-765 Arizona (July 2000-present) High Group: 04 for 764, 02 for 765
528-529 Utah (1936-May 1990) High Group: 99 (exhausted)
646-647 Utah (May 1990-present) High Group: 08
530 Nevada (1936-April 1997) High Group: 99 (exhausted)
680 Nevada (April 1997-present) High Group: 11
531-539 Washington (1936-present) High Group: 67 for 531, 65 for 532-539
540-544 Oregon (1936-present) High Group: 77 for 540-544
545-573 California (1936-September 1987) High Group: 99 (exhausted)
602-626 California (September 1987-present) High Group: 75 for 602-613, 73 for 614-626
574 Alaska (1936-present) High Group: 55
575-576 Hawaii (1936-August 2004) High Group: 99 (exhausted)
750-751 Hawaii (August 2004-present) High Group: 14 for 750, 12 for 751
577-579 Washington DC (1936-present) High Group: 49 for 577, 47 for 578-579
580 Virgin Islands (1936-present) High Group: 39
581-584 Puerto Rico (1936-February 1985) High Group: 99 (exhausted)
596-599 Puerto Rico (February 1985-present) High Group: 88 for 596-598, 86 for 599
585 (see New Mexico 525)
586 Somoa/Philipines/Guam (1964-present) High Group 63
587 Mississippi (see Mississippi 425-428)
588 Mississippi (see Mississippi 425-428, 587)
589-595 Florida(see Florida 261-267)
596-599 Puerto Rico (see Puerto Rico 581-584)
600-601 Arizona (see Arizona, 526-527)
602-626 California (see California 545-573)
627-645 Texas (see Texas 449-467)
646-647 Utah (see Utah 528-529)
648-649 New Mexico (see New Mexico 525, 585)
650-653 Colorado (see Colorado 521-524)
654-658 South Carolina (see South Carolina 247-251)
659-665 Louisiana (see Louisiana 433-439)
666-not assigned
667-675 Georgia (see Georgia 252-260)
676-679 Arkansas (see Arkansas 429-432)
680 Nevada (see Nevada 530)
681-690 North Carolina (see North Carolina 237-246)
691-699 Virginia (see Virginia 223-231)
700-728 Railroad Workers (1936-July 1963, but could be 1964) High Group: 18 for 700-726, 10 for 727, and 14 for 728
729-733 Enumeration at Entry (2003-present) High Group: 16 for 729-731, 14 for 732-733
734-749 unassigned
750-751 Hawaii (see Hawaii 575-576)
752-755 Mississippi (see Mississippi 425-428, 587, 588)
756-763 Tennessee (see Tennessee 408-415)
764-765 Arizona (see Arizona 526-527)
766-772 Florida (see Florida 261-267)
773-899 unassigned, for future use
900-999 unassigned

Note: There are tax ID numbers that start with a "9". They also have a "7" or an "8" as the fourth digit (first of the middle two).


Until 1959, all area numbers were 584 and below
Until 1964, all area numbers were 585 and below
Until 1980, all area numbers were 587 and below
Until 1983, all area numbers were 596 and below. In March of 1983, the first social security numbers that began with a "6" were issued in Arizona).
In 2000, the social security numbers that began with a "7" were issued, also in Arizona.

Keep in mind, these facts do not include the Railroad Workers, as their numbers were between 700-728.

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