Carnildo

So Tangram-ES only supports building from a git repository, not from the source tarball? If so, the documentation should mention this.

north-america/us/USGSImagery.geojson and north-america/us/USDA-NAIP.geojson are in the public domain as works of the US federal government. I'm not sure what sort of license URL would work here -- the public-domain status...

In regards to fees, I checked the data at http://www.uscampgrounds.info/index.html for the western United States. About 10% of the campgrounds listed are "free or under $12"; spot-checking those suggests that...