When intersecting wilderness areas with the trail, wilderness areas may be a single MultiPolygon for a wilderness area. So when I intersect wilderness areas with the trail, I see polygons way out in Nevada, that aren't connected to California.
Instead, first split the multipolygons into individual polygons (keeping the attributes), then intersect. It might even be better to do two steps, first an intersection with the multipolygons, and then split into polygons, because then there's less data in the reshape.
When intersecting wilderness areas with the trail, wilderness areas may be a single MultiPolygon for a wilderness area. So when I intersect wilderness areas with the trail, I see polygons way out in Nevada, that aren't connected to California.
Instead, first split the multipolygons into individual polygons (keeping the attributes), then intersect. It might even be better to do two steps, first an intersection with the multipolygons, and then split into polygons, because then there's less data in the reshape.