The lines are the US Forest Service's National Forest System trails layer (public domain), read 2026-10-16 and simplified for the map; the length is the line's, end to end, and the class, surface, grade and tread width are the forest's own entries where it publishes them - a forest that publishes the centreline alone has none. The trailheads and the points along the way are the Service's recreation points, and the write-ups its own recarea text, unedited. Heights come from USGS 3DEP through Terrain Tiles on AWS (Mapzen/Tilezen), read along each line and rounded; a short trail on steep ground can be off by a few tens of feet. Closures change: check the forest's own site before you go.
