In 1841 the wagon train was around 70 people, and in 1842 around 100, but in 1843 as a result of “encouragement” (maybe propaganda is more accurate) by the government and other hucksters the wagon train was 1,000 strong plus 5,000 oxen and cattle.
The Oregon Territory was not even technically part of the U.S. yet — this did not happen until 1846 when Britain just handed it over for free, essentially — but over the preceeding 30 years fur trappers and traders, missionaries, and other pioneers had established a trail from Missouri.
The Oregon Trail was laid by fur traders and trappers from about 1811 to 1840 and was initially only passable on foot or horseback. By 1836, when the first migrant wagon train was organized in Independence, Missouri, a wagon trail had been cleared to Fort Hall, Idaho. Wagon trails were cleared increasingly farther west and eventually reached the Willamette Valley in Oregon, at which point what came to be called the Oregon Trail was complete, even as almost annual improvements were made in the form of bridges, cutoffs, ferries, and roads, which made the trip faster and safer. From various starting points in Iowa, Missouri, or Nebraska Territory, the routes converged along the lower Platte River Valley near Fort Kearny, Nebraska Territory. They led to fertile farmlands west of the Rocky Mountains. From the early to mid-1830s (and particularly through the years 1846–1869) the Oregon Trail and its many offshoots were used by about 400,000 settlers, farmers, miners, ranchers, and business owners and their families to get to the area known as Oregon and its surrounding counterparts. The eastern half of the trail was also used by travelers on the California Trail (from 1843), Mormon Trail (from 1847), and Bozeman Trail (from 1863) before turning off to their separate destinations. Use of the trail declined after the first transcontinental railroad was completed in 1869, making the trip west substantially faster, cheaper, and safer.
It was 2,170 miles long. They rode on horseback or in covered wagons, and many died along the way from drownings during river crossings, disease, injuries, Indian attacks, and more.
A map:
