The Uinta Highline Trail runs the length of the high Uinta mountain range through the High Uintas Wilderness in northeastern Utah. It is a true wilderness trail, and does not intersect a road for at least 70 miles. The trail is around 100 miles long, but most backpacking trips are done over a 70 mile section between Chepeta Lake and Hayden Pass.

This is from the Denver Water website:
The High Line Canal, designated as a National Landmark Trail, was completed in 1883 to deliver irrigation water. Today, the canal is owned and operated by Denver Water. The canal trail has become a major recreational amenity in the Denver area, as people enjoy using the canal’s trail for hiking, biking, jogging and horseback riding.