I was looking at the naming convention for US blockgroups but could not find and reliable documentation for it. US Census website mentioned somewhere that the 5 digit US county code can be split as XXYYY where XX denotes the state code and YYY denotes an the county id within that state. Is there a similar convention for US blockgroups as well? I believe they use the FIPS system but wanted to get some more information on that.

Alternately, is there a source where I can get naming conventions for all these geospatial types?

1 Answer 1


Yes indeed, block groups are formatted like:


where S = State, C = County, T = Tract, and G = Block Group. Blocks have an additional three digits beyond that.

Reference: https://www.census.gov/geo/reference/geoidentifiers.html *click on "GEOID Structure for Geographic Areas".

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.