The patient State/county FIPS code (PSTCO_GEO) is assigned based on the geographic centroid of the ZIP Code. Nearly 25 percent of U.S. ZIP Codes cross county lines; using the geographic centroid allows for a consistent approach in assigning county code to these records.
The county of the geographic centroid of the ZIP Code is identified using the SASHELP.ZIPCODE lookup file from SAS®.
Additional information from SAS on the geocode procedure is available at SAS Geocode Procedure at http://support.sas.com/documentation/cdl/en/graphref/65389/HTML/default/viewer.htm#n1cqwrpowwd4l6n1lmw39ughjpuh.htm.
PSTCO_GEO contains unmodified FIPS county codes. Unmodified FIPS county codes include unique values for independent cities, such as Baltimore City and St. Louis City.
FIPS codes include values for outlying areas of the United States and freely associated States (i.e., American Samoa, Federated States of Micronesia, Guam, Marshall Islands, Commonwealth of the Northern Mariana Islands, Palau, Puerto Rico, U.S. minor outlying islands, and the U.S. Virgin Islands).
If there is no associated county for the ZIP Code, PSTCO_GEO would be set to invalid. If the ZIP Code is missing, foreign ('F') or homeless ('H'), PSTCO_GEO would be set to missing.