As the website states:
> NPMaps.com is an independent website and is not affiliated with the National Park Service.
> This is just a one-man project that gets worked on whenever said guy actually has some free time. It's hard work!
This is particularly important as NPS actually has an official Mapbox based initiative underway, here:
https://github.com/nationalparkservice
In an attempt to unite their various datasets from around the country into one large system.