Lonesome Highway — Pawnee National Grassland to Crow Butte via the South Platte High Plains Back Road

The northeastern corner of Colorado is so empty it makes the San Juans feel crowded. From the Pawnee Buttes trailhead on County Road 390 in Weld County, a network of maintained gravel and two-track roads runs north and east through Pawnee National Grassland toward the Wyoming and Nebraska lines, passing through country that looks almost identical to what Lieutenant John C. Frémont crossed in the 1840s. The Pawnee Buttes themselves — twin Oligocene sedimentary pillars rising 300 feet above the surrounding plain — anchor the western end. East of there the road drops into the South Platte River breaks at Crook, Colorado, with views into the Crow Butte badlands where the geology starts turning interesting again. Antelope are everywhere. Ferruginous hawks own the fence posts.

This is easy terrain by technical standards — high-clearance 2WD handles it in dry conditions, though wet gumbo clay after rain will strand a vehicle fast. No lockers required, but don’t underestimate the mud. Best April through June for wildflowers and fall migration birding; summer is brutal heat and rattlesnakes. No permit required. Water is scarce — carry all of it. Fuel in Sterling or Greeley. Dispersed camping is allowed throughout the Grassland with no fee. The payoff here isn’t technical challenge; it’s the absolute silence of the high plains and skies so wide they feel like a different planet.