According to the Census Bureau, "GEOIDs are numeric codes that uniquely identify all administrative/legal and statistical geographic areas for which the Census Bureau tabulates data."

At a practical level, GeoIDs (also called FIPS Codes) are different combinations of those Census identifiers. Depending on the data you're working with, you might need a different length of GeoID.

GeoIDs, or FIPS codes, can be up to 40 digits. The more digits there are, the more granular of a measurement it is.

Geocodio returns FIPS codes, and from those FIPS codes, you can create the GeoID you need based on the required number of digits.

How to build a GeoID

GeoIDs are built based on a combination of Census FIPS codes, which are unique identifiers for differnet levels of geographic data. The largest geographic area covered by a FIPS code is the State, and the smallest is the Block. Here's the order of FIPS codes, in declining order of size:

• State
• County
• Tract
• Block Group (i.e. a group of Blocks)
• Block

Geocodio will return these FIPS codes levels to you, and then you can build the GeoID you need.

Let's use 1600 Pennsylvania Avenue, Washington DC as an example:

Look up more Census data for addresses

Geocodio can also help you add historical (past-year) Census FIPS codes, blocks, and tracts to addresses or coordinates. Data is available for the 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 and 2022 Census years.

Our Census data append includes:

• Census year
• State FIPS
• County FIPS
• Place Name
• Place FIPS
• Full FIPS (concatenation of State, County, and Place)
• Tract code
• Block code
• Block group
• Metro/Micro Statistical Area (MSA)
• Combined Statistical Area (CSA)
• Metropolitan Division
• County Subdivision: Minor Civil Division (MCD) / Census County Division (CCD)

More of a visual learner? Watch a video