The rich farmlands of Oregon drew thousands of settlers. The land was free to those who could make it the Oregon Territory. People who were farming on marginal lands in Indiana, illinois and Missouri found the lure of rich farmland in the Willamette valley irresistible.The Oregon Territory stretched from the Pacific coast to the Rocky Mountains, encompassing the area including present-day Oregon, Washington, and most of British Columbia. Originally Spain, Great Britain, Russia, and the United States claimed the territory.Background. Early 1800s, traders and trappers came into the area from Canada, Russia, Latin America and the United States. 1830s and 1840s, other settlements were created in the Willamette River valley. These settlers generally came from Midwestern and eastern states, Canada and Russia.There were many reasons for the westward movement to Oregon and California. Economic problems upset farmers and businessmen. Free land in Oregon and the possibility of finding gold in California lured them westward.Starting in the 1840s, settlers from the east began to travel to Oregon Country using the Oregon Trail. Over the next 20 years, hundreds of thousands of people migrated west, many of them settling in Oregon. Eventually, there were so many Americans in the region that Great Britain gave up the land.