Established after the Dust Bowl to prevent further soil erosion, the Cimarron National Grassland is dominated by three ecosystems—shortgrass prairie, sand sage prairie, and wooded riparian. The Sea of Grass, a self-guided auto tour, takes you 30 miles through the three ecosystems and along the National Historic Santa Fe Trail, marked by limestone posts. The 23 miles of the Santa Fe Trail form the longest portion of this famous route on public land. You can bike, hike, or ride horses on a companion trail. If you don't want to follow the entire auto tour, take time to stop at the Santa Fe Trail historic sites of Middle Spring (NRHP) and Point of Rocks (NRHP). To find these go from Morton in Elkhart 7½ miles north on K-27, cross the Cimarron River bridge, and turn west. More than 345 bird species (including roadrunners), as well as pronghorn, elk, and mule and whitetail deer, live in the grassland.