Travels by fur trappers and adventurers, such as Manuel Lisa and Jim Bridger from 1807 to 1840, completed the exploration of the region. With the decline of the fur trade in the late 1840s and much of the prized beaver long since made scarce by over-trapping, few white explorers entered the forest over the next few decades. The first federally financed expedition which passed through portions of Shoshone National Forest was the Raynolds Expedition of 1860, led by topographical engineer Captain William F. Raynolds. The expedition included geologist and naturalist Ferdinand Vandeveer Hayden and was guided by mountain man Jim Bridger. Though the Raynolds Expedition was focused on exploration of the Yellowstone region, several efforts to enter what later became Yellowstone National Park were impeded by heavy snows across the mountain passes such as Two Ocean Pass. The expedition finally crossed the northern Wind River Range at a pass they named Union Pass and entered Jackson Hole valley to the south of Yellowstone. Hayden led another expedition through the region in 1871. Hayden was primarily interested in documenting the Yellowstone country west of the forest, but his expedition also established that the forest was a prime resource that merited protection. Travels in the forest in the 1880s by later U.S. President Theodore Roosevelt, who was also a strong advocate of land conservation, as well as by General Philip Sheridan, provided the impetus that subsequently established the Yellowstone Timberland Reserve in 1891, creating the first national forest in the U.S.