The Colorado Trail Explorer online map includes details of paved and unpaved trails for hiking, bicycling and motorized vehicles. The state is developing a mobile app for the maps.
Developed by Colorado Parks and Wildlife, it includes 17,099 trails and 1,431 trailheads.
https://cts.state.co.us/cotrex/desktop/
See the complete article by Chuck Hickey at Fox31 Denver:  http://kdvr.com/2017/06/02/new-online-interactive-map-shows-of-every-kind-of-trail-in-colorado/