PPA and federal parks icon is the same
The Passport America Parks and the US federal parks have the same or at least a very close appearing icon. A US flag. I don't know if you control this but how about changing one or the other. Maybe a US for the USFS and NPS parks. Or a PA for the PPA parks.
As is it is tough to separate the PPA parks from the others especially around major federal parks like Glacier where the are many USFS cg. And few if any PPA.