It is possible to apply unique per-country styles to administrative boundary lines if you are using the mapbox.mapbox-streets-v6
vector tile source. (You can check and adjust this in the Layers panel of Mapbox Studio Classic.)
In the #admin
layer there is a field called iso_3166_1
that you can use to create a filter in CartoCSS. All of the admin level 4 boundaries in the US will have a iso_3166_1
code of US
, so create a style like this:
#admin[admin_level=2] {
// styles for country boundaries go here
}
#admin[admin_level=4][iso_3166_1='US'] {
// styles for US state boundaries go here
}
Values of the iso_3166_1
field will match the ISO 3166-1 alpha-2 standard. For boundaries that separate two countries, the code for each country will be included in alphabetical order and separated by a dash. Eg the US-Mexico border would be MX-US
.