How Social Security Numbers are Assigned

Learn how Social Security Numbers are assigned
An overview of how social security numbers are assigned.

How Are Social Security Numbers Assigned?

This article aims to help you understand how Social Security Numbers are assigned. In 2011, the Social Security Administration (SSA) changed how they assign Social Security Numbers (SSNs). The new method uses a process called “randomization” to assign SSNs.

The Administration developed a new method to help protect the SSN’s integrity and extend the nine-digit SSN’s longevity (instead of adding additional digits).

SSN Randomization changes the assignment process in several ways. First, it eliminates the geographical importance of the first three digits. Also, the new randomization process eliminates the significance of the highest group number.

As a result, the High Group List is frozen in time and can only be used to see the area and group numbers SSA issued before the randomization implementation date.

Overview of Social Security Numbers

A Social Security number is issued to U.S. citizens, permanent residents, and temporary workers in the United States. The number is issued to an individual by the SSA, an agency of the federal government.

Its primary purpose is to track working individuals for taxation purposes and Social Security benefits. Since it was initially introduced, the SSN has become the primary national identification number, even though it was not originally intended to be used as a form of identification.


Since 1972, numbers have been issued by the central office. The first three (3) digits of a person’s social security number are determined by the ZIP Code of the mailing address shown on the application for a social security number.

Previously, before 1972, social security numbers were assigned by SSA field offices. The number merely established that his/her card was issued by one of the SSA offices in that State.


In 2011, the SSA changed the assignment process to a process known as SSN randomization. This process eliminates the geographical significance of the number’s first three digits. Below is an explanation of how the numbers were assigned under the old system that was in effect before 2011.

Social Security Number – Area Group Serial

The Social Security number consists of nine (9) digits, usually written in the format – 1 2 3 – 4 5 – 6 7 8 9. The first three digits of a social security number denote the area (or State) where the original Social Security number application was filed.

Each area’s group number (middle two (2) digits) ranges from 01 to 99 but is 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.

Within each group, the serial numbers (last four (4) digits) run consecutively from 0001 through 9999.

The chart below shows how Group numbers are assigned:

  • ODD – 01, 03, 05, 07, 09——EVEN – 10 to 98
  • EVEN – 02, 04, 06, 08——ODD – 11 to 99

List of Social Security Number Prefixes for Each State

Following is a list of social security number prefixes for each state. The listing is organized in ascending order based on the SSN prefix, with the corresponding issuing state listed. Remember, these apply only to numbers issued before 2011 under the old system.

SSN Prefix = Issuing State

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
211-222 = Delaware
223-231 = Virginia
232 = North Carolina
232 = West Virginia
233-236 = West Virginia
237-246 = North Carolina
247-251 = South Carolina
252-260 = Georgia
261-267 = Florida (Also 589-595)
268-302 = Ohio
303-317 = Indiana
318-361 = Illinois
362-386 = Michigan
387-399 = Wisconsin
400-407 = Kentucky
408-415 = Tennessee
416-424 = Alabama
425-428 = Mississippi
429-432 = Arkansas
433-439 = Louisiana
440-448 =Oklahoma
449-467 = Texas
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
525 = New Mexico
526 = Arizona
526 = New Mexico
527 = Arizona
528 – 529 = Utah
530 = Nevada
531 – 539 = Washington
540 – 544 = Oregon
545-573 = California
574 = Alaska
575-576 = Hawaii
577-579 = District of Columbia
580 = Virgin Islands
580-584 = Puerto Rico
585 = New Mexico
586 = Guam & American Samoa
586 = All Other Pacific Territories
587-588 = Mississippi
589-595 = Florida (also 261-267)
600-601 = Arizona (designated)
602-626 = California (designated)
700-728 = Railroad Retirement
729-999 = Not used until randomization was introduced.

Note: The number 666 has never been used and will not be used in the future.

Please post a comment below if you are aware of any new number ranges.

SSN Requirements

No law directly requires a natural-born United States citizen to apply for a Social Security number to live or work in the United States. However, some people still live without a number because they view it as a voluntary government program. Those who don’t get a number find it difficult to engage in ordinary acts of commerce or banking activities because they can’t provide an SSN.

Additional Resources

If you want to learn more about the process, visit the Social Security Administration website. On the website, you can:

  • Get more information on how numbers are assigned and the randomization process
  • Find the offices near you and get directions using the office locator. Just enter your zip code.
  • Learn how to get cards and how to request replacement cards

Questions and Comments

If you have any questions, please post a comment below.


  1. What does a Social Security beginning with 200-75-XXXX indicate? I really didn’t understand the middle number, but I believe the first 3 numbers indicate under the old system that the number was applied for in PA.

  2. I didn’t know the numbers were randomized rather than regionalized which makes a lot of sense. I’m a 370 from Michigan. Odd question… why is the prefix 666 unavailable? It’s just a number. I understand it’s Christian significance but it is only a series of digits and this is not a “Christian” domain. I am actually, but my faith is mine not someone else’s concern. The relevance of that number is from The New Testament (St. John’s Revelation)… and that is not fully explained or understood.

  3. i need my grandfathers ssn because he has passed recently and ppl are still calling to collect nothing but they dont believe me they want his number
    how can i get it

    • If you are a family member, then you need to look at the DEATH CERTIFICATE. The social security number will be on it. Contact the funeral home, they will have a copy in their files. If you dont; know who handled the service, contact the cemetary, their records should show who the funeral director was. WARNING, if you are not a DIRECT family member no one will give you a copy or any information.

  4. Is a SSN that has the first 5 digits all matching valid? I came across one on a client’s paperwork that had all the same number in the first 5 places. Only the last 4 were different.

    • I can’t say whether or not the numbers in your particular case are valid, but it would have been possible under the “old” system of issuing numbers. The first three numbers are based don’t the geographic area. The next two numbers are the group numbers, and those numbers are allocated to particular areas within a state.

  5. You say that 729-999 are not in use, but my wife has a SSN that starts with 881. She is from France and got a green card in 2012, and that was the prefix assigned.

  6. Can a person’s prefix be different from the state the were born in? My prefix suggests I was born in Washington, but I was not.

  7. With the advent of some financial institutions wishing to make you give them the last six or your social security number, it seems as though they do not understand nor does the government understand the sanctity that should be afforded Social Security identification numbers. With crooks having access to screaming fast computers today, it really is not much of a problem with a nine-digit password to eventually obtain it by searching. And it makes it much easier with the last four that the majority of institutions require for identification. However, with the last six, you might as well just give them the entire number and see your personal security go down the tube. This should be a top priority of our government to band the use of any more numbers being given out to anybody for identification.

  8. Please remember: the SSN is assigned based on the address provided on the application submitted to the Social Security Administration. This address is supposed to be the applicant’s permanent address. If you have a question, you should contact the Social Security Administration.
    The U.S. SSN (Social Security Number) is assigned RANDOMLY. However, the methodology is not public knowledge.

  9. Concerning? I was noting my son’s ssn this year while gathering tax information, and it starts with 881. My concern is that it won’t be valid when he goes to work- as it says numbers starting with 729-999 = Currently not in use????
    What could have happened?

  10. I am a Veteran living in the Houston, Texas area and am enrolled in VA Healthcare. I have recently discovered, when checking in at the DeBakey VA Hospital in Houston, that their VA computer shows that there are 3 Veterans in their system,
    including myself, that have the same exact last name and the same exact last 4 numbers of their SSN. Should I be concerned?

    • We’re not in a position to interpret whether it is something that should be of concern. However, it may be something that you should inquire about with VA Healthcare. It is possible that you may have multiple accounts within their system. The records that you see with the same last name and same last four numbers of the SSN may all be referring to you. You may want to give them a call to get more information.

  11. Both my kids born 2004 & 2009 are 766 and it’s now required to file for them at birth to which they were born in FL but it says the 766 aren’t in use yet when they have been in use for at least 15years now. Strange.

  12. I live in NE. Everyone in my family and my first born all start with the 505, 508. This past year I had a baby. His SSN starts with 358. Why is this?

    • your would indicate you and your family was born in Nebraska, But your sons would indicate he was born in Illinois, so if he wasn’t that is strange, better check into so he don’t have problems later in life with his number

    • its not where you were born that determines the number, it is the state where the application for an original Social Security number was filed. In my case, I didn’t file till I was 13 and had moved multiple times.

    • The numbers are now picked at random & are not picked by state. The first three numbers of your baby’s ssn have nothing to do with his state of birth or the state in which his ssn was applied for. Since 2011, the Social Security Administration has been assigning SSNs by randomization. This process eliminates the geographical significance of the first 3 numbers.

  13. I was born in 1980 so my social security number should be from the state I was born in since the change was not started till 2011 where your social security number is pick random

  14. My daughter was born in Connecticut it was issued a social security number while living in Connecticut but she has a New York social security number

  15. I was born in Georgia and I have a New York number. My cousin was born the same month and in the same hospital as me and she has a Georgia number. What could be the reason?

    • I was born in Alabama, but my SSN was issued at about age 8 (this was many years ago) while living in North Dakota. Therefore, I have a North Dakota SSN.

  16. i have a question it says the 1st 3 numbers say where one was born i have 149 the list says that is the number for new Jersey and i was born in Oklahoma. why?

    • The first three numbers actually represent the geographic area where the social security number was issued, rather than where a person was born.


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