This route is super special because the trail from Harts Pass Trailhead leads to the Northern Terminus of the Pacific Crest Trail is on the U.S./Canada border. The trail can be done in either direction.  Getting to/from the Northern Terminus is not included in the FKT.  The next section is between Harts Pass and Rainy Pass.

Old swedish pilgrims' way, from Riseberga Abbey to Olshammar (Birgittakyrkan). Nowadays about ten percent paved road, 40–50 percent dirtroad and the rest singletrack.