Arkansas, Cimarron, and Canadian rivers that drain the region vary by 90 or more percent in their flows during an average year. Also on this trail, unlike the Oregon Trail, there was a serious danger of Indian attacks, for neither the Comanche nor the Apache of the southern high plains tolerated trespassers. In 1825, Congress voted for federal protection for the Santa Fe Trail, even though much of it lay in the Mexican territory. Lack of food and water also made the trail very risky. Weather conditions, like huge lightning storms, gave the travelers even more difficulty. If a storm developed, there was often no place to take shelter and the livestock could get spooked. Rattlesnakes often posed a threat, and many people died due to snakebites. The caravan size increased later on to prevent Indian raids. The travelers also harnessed more oxen instead of mules—primarily for the greater hauling power of oxen but also because they were less valued by Indians and thus less risk of being raided. Historic preservation Segments of this trail in Missouri, Kansas, Oklahoma, and New Mexico are listed on the National Register of Historic Places. In Missouri, this includes the 85th and Manchester "Three Trails" Trail Segment, Arrow Rock Ferry Landing, Santa Fe Trail – Grand Pass Trail Segments, and Santa Fe Trail – Saline County Trail Segments. The longest clearly identifiable section of the trail, Santa Fe Trail Remains, near Dodge City, Kansas, is listed as a National Historic Landmark. In Colorado, Santa Fe Trail Mountain Route – Bent's New Fort is included on the National Register. Notable features Missouri Arrow Rock (Arrow Rock Landing, Santa Fe Spring, Huston Tavern) Harvey Spring/Weinrich Ruts Independence (Santa Fe trail Ruts, Lower Independence (Blue Mills) Landing, Upper Independence (Wayne City) Landing. Kansas City (Westport Landing) Kansas Kansas City (Shawnee Mission, Big Blue River Crossing) Council Grove (Kaw Mission, Neosho River Crossing, Hermit's Cave, Last Chance Store, Council Oak, Post Office Oak) Fort Larned National Historic Site Fort Dodge (Jackson's Grove and Island, Santa Fe Trail Ruts, Middle Crossing, Point of Rocks, Fort Atkinson Site) Mountain Route towards Colorado Arkansas River Crossing Colorado Mountain Route Bent's Old Fort National Historic Site Raton Pass Cimarron Route thru Kansas towards Oklahoma Cimarron River Cimarron National Grassland New Mexico Mountain Route Clifton House Cimarron (Aztec Mill, Cimarron Plaza and Well) Philmont Scout Ranch Cimarron Route Kiowa National Grassland Joint route