The Continental Divide Trail (CDT) runs roughly 3,100 miles along the spine of North America, tracing the rugged backbone of the Rocky Mountains from the scorched deserts of southern New Mexico to the glaciated wilderness of northern Montana. It crosses five states and dozens of mountain ranges, where lightning storms roll across open sky and elk bugle through dawn mist. In Colorado, it climbs to dizzying heights above 13,000 feet, where snow can linger deep into summer and the thin air sharpens every breath. In Wyoming, it weaves through the surreal geysers and grizzly country of Yellowstone, then across the stark beauty of the Great Divide Basin, where no rivers flow to the sea. The trail ends, or begins, at the remote edge of Glacier National Park on the Canadian border, but much like the shifting line it follows, the CDT is less a trail and more a test of spirit. Once walked, it carves itself into the soul.