choroplethr requires you to use the naming convention in the "region" column (i.e. the numeric version of the FIPS code - no leading zero).

data(county.regions)

See also

?county.map

Examples

data(county.regions) head(county.regions)
#> region county.fips.character county.name state.name state.fips.character #> 1 1001 01001 autauga alabama 01 #> 36 1003 01003 baldwin alabama 01 #> 55 1005 01005 barbour alabama 01 #> 15 1007 01007 bibb alabama 01 #> 2 1009 01009 blount alabama 01 #> 16 1011 01011 bullock alabama 01 #> state.abb #> 1 AL #> 36 AL #> 55 AL #> 15 AL #> 2 AL #> 16 AL