Once across the Snake River ford near Old Fort Boise the weary travelers traveled across what would become the state of Oregon. The trail then went to the Malheur River and then past Farewell Bend on the Snake River, up the Burnt River canyon and northwest to the Grande Ronde Valley near present-day La Grande before coming to the Blue Mountains. In 1843 settlers cut a wagon road over these mountains making them passable for the first time to wagons. The trail went to the Whitman Mission near Fort Nez Perces in Washington until 1847 when the Whitmans were killed by Native Americans. At Fort Nez Perce some built rafts or hired boats and started down the Columbia; others continued west in their wagons until they reached The Dalles. After 1847 the trail bypassed the closed mission and headed almost due west to present-day Pendleton, Oregon, crossing the Umatilla River, John Day River, and Deschutes River before arriving at The Dalles. Interstate 84 in Oregon roughly follows the original Oregon Trail from Idaho to The Dalles.

Kroll, Helen. “Books that Enlightened the Emigrants.” Oregon Historical Quarterly (June 1944): 102-123. Fort Laramie was the end of most cholera outbreaks which killed thousands along the lower Platte and North Platte from 1849 to 1855. Spread by cholera bacteria in fecal-contaminated water, cholera causes massive diarrhea, leading to dehydration and death. In those days its cause and treatment were unknown, and it was often fatal—up to 30 percent of infected people died. It is believed that the swifter flowing rivers in Wyoming helped prevent the germs from spreading. [53] Colorado [ edit ] Rollins, Philip Ashton (1995). The Discovery of the Oregon Trail: Robert Stuart's Narratives of His Overland Trip Eastward from Astoria in 1812–13. University of Nebraska. ISBN 978-0-8032-9234-5. Brooks D. Simpson; Ulysses S. Grant: Triumph Over Adversity, 1822–1865; 2000, ISBN 978-0-395-65994-6, p. 55From the letter of Betsey Bayley, in Covered Wagon Women, Volume 1, by Kenneth L. Holmes, ebook version, University of Nebraska Press: Lincoln, 1983, p. 35.

Enoch Conyers was on the Oregon Trail the same year as J.T. Kearns. Conyers was also a farmer and was impressed by the abundance of grazing land in the Bear River Valley. Continued emigration added sufficient population by 1846 to aid U.S. negotiators in securing the Oregon Treaty with Great Britain, which described Oregon as the land north of the 42 nd Parallel, east to the Continental Divide, and north to the 49 th Parallel. With just over 5,000 inhabitants, Oregon secured territorial status from Congress in 1848, and the territory’s population topped 12,000 by 1850. From the earliest decades of the Republic, groups of migrants headed west from the established states to stake out homesteads on the western periphery of institutional society. They traveled first across the Appalachian Mountains into the Old Northwest—today’s states of Ohio, Indiana, Illinois, and Michigan—then from the South to populate Alabama, Mississippi, Arkansas, Missouri, and Iowa. By the 1820s, some politicians called for resettlement in the Oregon Country, a relatively un-resettled region over which the United States and Great Britain jointly claimed sovereignty by treaty in 1818. The penetration of the fur trade into the region during the 1820s and 1830s, especially on the Upper Missouri and the Columbia river basins, exposed both the natural wealth of the region and the presence of Native populations. During most of this westward movement, overland trails and river passages were essential conduits of people, trade, and institutional expansion.While the first few parties organized and departed from Elm Grove, the Oregon Trail's primary starting point was Independence, Missouri, or Westport, (which was annexed into modern day Kansas City), on the Missouri River. Later, several feeder trails led across Kansas, and some towns became starting points, including Weston, Fort Leavenworth, Atchison, St. Joseph, and Omaha. Williams, Joseph (1921). Narrative of a Tour from the State of Indiana to the Oregon Territory in the Years 1841–2 (DJVU). Standard. ISBN 978-0-87770-172-9. OCLC 2095243. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sourcesin this section. Unsourced material may be challenged and removed. ( May 2017) ( Learn how and when to remove this template message)

While fur traders made their own rudimentary routes in the Pacific Northwest throughout the 1700s, the formal Oregon Trail was mostly used between 1840 and 1870. It became nearly obsolete with the completion of the first Transcontinental Railroad in 1869. By taking the train, settlers from the East could arrive in the Pacific Northwest in one week versus six months. Reasons for Its Establishment Unruh, John D (1993). The Plains Across the Overland Emigrants and Trans-Mississippi West 1840–1860. University of Illinois Press. pp.392, 512. ISBN 978-0-252-06360-2. Many who went were between the ages of 12 and 24. Between 1860 and 1870, the U.S. population increased by seven million; about 350,000 of this increase was in the Western states.A branch of the Oregon trail crossed the very northeast corner of Colorado if they followed the South Platte River to one of its last crossings. This branch of the trail passed through present-day Julesburg before entering Wyoming. Later settlers followed the Platte and South Platte Rivers into their settlements there (much of which became the state of Colorado). Kaiser, Leo, and Priscilla Knuth, eds. “From Ithaca to Clatsop: Miss Ketcham’s Journal of Travel, Pt. 2.” Oregon Historical Quarterly(December 1961): 397. Lillian Schlissel, "Women's diaries on the western frontier." American Studies (1977): 87–100 online. The Oregon Trail's nominal termination point was Oregon City, at the time the proposed capital of the Oregon Territory. However, many settlers branched off or stopped short of this goal and settled at convenient or promising locations along the trail. Commerce with pioneers going further west helped establish these early settlements and launched local economies critical to their prosperity.