I've got county-level data from USDA NASS, and I want to merge it with gridded climate data. A preliminary step is the associate the counties with the coordinates of their centroids. If I merge by names, about 5% of the counties are left out, because of different representations of names. For example, the city and county of Chesapeake, Virginia is listed as "Chesapeake" in GADM and "Chesapeake City" in the NASS data.

The NASS data has ANSI codes, while the GADM data has its own scheme. Is there some sort of concordance table or dictionary that allows me to link these two?

Here is an example of the NASS data: http://quickstats.nass.usda.gov/results/E03CA5B5-AE87-3C9D-B8E7-662F85AD3CC0

And here is an example of the GADM data:

2> library(raster)
2> adm <- getData('GADM', country='USA', level=2)
trying URL 'http://biogeo.ucdavis.edu/data/gadm2.7/rds/USA_adm2.rds'
Content type 'unknown' length 13936198 bytes (13.3 MB)
downloaded 13.3 MB

2> head(adm)
1        1  244 USA United States    1 Alabama    1 Autauga County    County
2        2  244 USA United States    1 Alabama    2 Baldwin County    County
3        3  244 USA United States    1 Alabama    3 Barbour County    County
4        4  244 USA United States    1 Alabama    4    Bibb County    County
5        5  244 USA United States    1 Alabama    5  Blount County    County
6        6  244 USA United States    1 Alabama    6 Bullock County    County
1        NA      <NA>
2        NA      <NA>
3        NA      <NA>
4        NA      <NA>
5        NA      <NA>
6        NA      <NA>

The county ANSI's don't appear to correspond to the GADM's ID_2 field.

  • @RobertHijmans Apologies for the late ping. I don't think your link addresses OP's request. I found this on google because like OP, I am looking for a lookup table or concordance that will link GADM's IDs for USA counties with more widely used identifiers for USA counties such as ANSI codes or FIPS codes. Does such a table exist?
    – qdread
    Jan 12, 2021 at 15:49


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy