Chadron State Park is Nebraska’s oldest state park, founded in 1921. It is situated in the northwest corner of the state, on the north side of Nebraska’s Pine Ridge, 9 miles south of the town of Chadron. This ridge is dominated by ponderosa pines and has over 100 miles of singletrack and doubletrack, great for running and mountain biking.

The GR50 is one of the longest routes in Portugal totally in mountain terrain.

It traverses the Penêda-Gerês National Park from West to East. 
 

https://www.walkingpenedageres.pt/en/grande-rota/

The Herriman Trail system is in the westernmost corner of the Boundary Waters Canoe Area Wilderness. Its 13 miles of trail connects Dovre, Herriman and Knute Lakes with Little Vermillion Lake which provides further access to waterways and portages of the Boundary Waters. It is far away from any large towns and is one of the least visited sections of this remote wilderness area.

This is a crazy fun route that starts at the edge of Whiskeytown lake. The whole run is on a fire road that varies in grade, however, is typically very steep. Due to the Carr fire in 2018 it is slightly burned, but the views are still breathtaking. Make sure to bring plenty of water and food as it is steep and can take longer than expected. This started at the gate which leads to Brandy Creek Falls.