What are the SSN prefixes for Colorado?

Colorado was assigned the area-number ranges 521-524, 650-653. A Social Security number issued there before 2011 begins with one of these three-digit numbers.

Does an SSN starting with 521 mean the person is from Colorado?

For cards issued before June 25, 2011, an SSN whose first three digits fall in Colorado's range was issued in Colorado, usually based on the mailing address on the application, not necessarily birthplace. Numbers issued after randomization carry no location meaning.

How can I check a specific number?

Use the SSN checker to enter a full number and see whether its structure is valid, which state it maps to, and a rough estimate of when it was issued.

Social Security Number Prefixes for Colorado

Area numbers 521-524, 650-653

area ranges: 2
lowest area number: 521
highest area number: 653
area numbers: 8

Colorado was assigned the Social Security area-number ranges 521-524, 650-653. Before SSA randomized number assignment in June 2011, any SSN beginning with one of these three-digit prefixes was issued in Colorado, generally based on the mailing address on the application. Newer numbers are assigned randomly and no longer indicate a state.

Colorado area-number ranges

Area-number range	Count
521-524	4
650-653	4

Sample Colorado SSN patterns

Estimated issue years for the lowest area/group combinations (illustrative):

Pattern	Estimated issued	Status
521-01-####	1936-1950	Valid
521-03-####	1936-1950	Valid
521-05-####	1936-1950	Valid
521-07-####	1936-1950	Valid
521-09-####	1936-1950	Valid
521-10-####	1936-1950	Valid
521-12-####	1936-1950	Valid
521-14-####	1936-1950	Valid
521-16-####	1936-1950	Valid
521-18-####	1936-1950	Valid
521-20-####	1936-1950	Valid
521-22-####	1936-1950	Valid
521-24-####	1936-1950	Valid
521-26-####	1936-1950	Valid
521-28-####	1936-1950	Valid
521-30-####	1936-1950	Valid
521-32-####	1936-1950	Valid
521-34-####	1936-1950	Valid
521-36-####	1936-1950	Valid
521-38-####	1936-1950	Valid
521-40-####	1936-1950	Valid
521-42-####	1937-1951	Valid
521-44-####	1938-1951	Valid
521-46-####	1939-1952	Valid

Frequently asked questions

What are the SSN prefixes for Colorado?: Colorado was assigned the area-number ranges 521-524, 650-653. A Social Security number issued there before 2011 begins with one of these three-digit numbers.
Does an SSN starting with 521 mean the person is from Colorado?: For cards issued before June 25, 2011, an SSN whose first three digits fall in Colorado's range was issued in Colorado, usually based on the mailing address on the application, not necessarily birthplace. Numbers issued after randomization carry no location meaning.
How can I check a specific number?: Use the SSN checker to enter a full number and see whether its structure is valid, which state it maps to, and a rough estimate of when it was issued.

Check a specific number with the SSN checker, or see all states.