I'm am a little on the conservative side. I think by trails most users are looking for hiking, horse, bike, 4wh trails like are on a National Geographic trails map, etc. . Unfortunately, there is no public source of detailed trail info for the Nation. The transportation data from Census has a few of these, however, it is far from complete as their mission (funding) is related to head and house counts for Congress.
A planimetric map is similiar to a topo map, but does not have contour lines. Other examples of planimetric maps would be Garmin City Navigator, OpenStreetMap (OSM) & Ibycus USA.
If you do not need the area north of 40 degrees, try Seldom's Desert SW mapset. He has made his routable and added trails from OSM data.