Geocorr Applications

These Geocorr (geographic correspondence engine) applications allow users to obtain geographic correspondence files (crosswalk files, correlation lists, etc.) for dozens of geographic layers for the United States. The various applications are nearly identical in what they do but vary in terms of the vintage of the datbase being accessed.

Versions

• Geocorr 2022 uses geography from the 2020 census and beyond.
• Geocorr 2018 adds the 115th and 116th congressional districts and 2016 state legislative districts.
• Geocorr 2014 works with available data through 2014.
• Geocorr 2000 uses geography from the 2000 census (with some updated fields as recent as 2008).
• Geocorr 1990 uses geography from the 1990 census. This is the original version.

Documentation

• The current help page applies to most versions of the application.
• The orginal help page is quite possibly the oldest document on this website. It was written circa 1996 to document this new-at-the-time application.
• The examples page illustrates several applications of Geocorr to different analysis scenarios.
• Videos of four sample runs were created circa 2010. They access the 2000 version of Geocorr, but the concepts still apply to any version.
• A Powerpoint presentation about Geocorr (36 slides) was presented at the 2015 Missouri GIS conference.
• Data allocation using geographic equivalency files is a very technical tutorial showing how geographic equivalency files can be used to allocate data summarized at one geographic level to another (source to target).

Notes

• Each of these Geocorr versions has its own link to a geographic glossary file. These Master Area Geographic Glossary of Terms pages provide brief descriptions of the geographic layers available for that version of Geocorr. (The link appears just below the Select State(s) box on the Geocorr form).
• The MABLE databases are almost entirely based on the Census Bureau's TIGER databases. These did not exist prior to 1990, so there are no versions of Geocorr that can access earlier years.
• Each version of MABLE is based on its own set of census blocks (1990, 2000, 2010, 2020). Geocorr cannot produce correlations between different decades, because the blocks change.
• When doing large extracts (e.g., when doing all states at once), use the Output Options section to turn off the report file output. Processing HTML (web page) output takes much longer than CSV files and may even cause Geocorr to time out.
• The MABLE databases are collections of state-based SAS datasets that can be directly accessed using MCDC's Uexplore/Dexter applications. Each state has three or four SAS data files, with [stab]v (e.g., alv, akv, ...) being a SAS view that merges the other datasets together to cover all the block geocodes for that state. Dexter can provide output in SAS dataset and DBF formats as well as CSV, HTML, and PDF. For more info about what's under the hood, see the "How Does Geocorr Work?" section of the Geocorr help page.