Oregon TrailPioneer overland route to the northwestern United States. About 2,000 miles long, about 2,000 miles long, the trail stretched from Independence, Missouri, to the Columbia River in Oregon. Part of the route followed the Platte River for 870 km (540 mi) through present-day Nebraska to Fort Laramie in present-day Wyoming. The trail continued along the North Platte and Sweetwater Rivers to South Pass in the Wind River range of the Rocky Mountains. From there the main trail went south to Fort Bridger, Wyoming, before turning into the Bear River Valley and north to Fort Hall in present-day Idaho. In Idaho the Oregon Trail followed the Snake River to Salmon Falls and then continued north past Fort Boise (now Boise). The route entered present-day Oregon, crossed the Grande Ronde River valley, crossed the Blue Mountains, and followed the Umatilla River to the Columbia River. Shorter, more direct routes were developed along some parts of the trail, but they were often more difficult. Originally, like many other major routes in the United States, sections of the Oregon Trail had been used by Native Americans and fur trappers. As early as 1742, part of the trail in Wyoming had been blazed by the Canadian explorer Pierre Gaultier de Varennes, sieur de La Vérendrye; the Lewis and Clark expedition, between 1804 and 1806, made it known more. German-American fur trader and financier John Jacob Astor, in establishing his trading posts, sent a party overland in 1811 to follow the trail of these explorers. Later, mountain men like James Bridger, who founded Fort Bridger in 1843, contributed their knowledge of the trail and often served as guides. The first caravan of emigrants, led by pioneering American physician Elijah White, reached Oregon in 1842.