Double black Crested Butte, CO
Slipper drops 147 vertical feet over feet of skiing, with a steepest pitch of 50°. That's steeper than 99% of the 2,251 double black runs we've measured in North America, and the 3rd steepest of 227 named runs at Crested Butte. It faces northeast.
Measured by ZRankings from 1-meter USGS lidar. Steepest pitch is the steepest stretch of about 50 vertical feet along the skiable line. Run lines come from OpenStreetMap and can sit a little off the skied path.