Even before Oregon Country—the disputed area claimed in the early 1800s by both Great Britain and the United States—was officially claimed by Congress as a United States territory in 1846, pioneers had been traveling west to explore its bounty. Meriwether Lewis and William Clark had arrived at the Pacific Ocean in 1805, but the route was much too hazardous for families to replicate while traveling by wagon.

In 1810, John Jacob Astor funded two separate expeditions—one by land and the other by sea—to establish a fur post at the mouth of the Columbia River. Enlistee Robert Stuart arrived via Cape Horn safely by ship, but after his vessel was blown up in an altercation with Native Americans, Stuart began an overland journey from Fort Astoria in present-day Oregon back to Missouri to request aid from Astor. During his yearlong voyage, Stuart became the first white man to discover a 20-mile gap in the Rocky Mountains through which wagons could safely pass.

In 1836, a small group led by Marcus and Narcissa Whitman made their way by wagon from New York to the Walla Walla Valley, where they established a mission for the Cayuse Indians, but it wasn’t until 1843 when the first mass migration of 1,000 pioneers set out from Independence, Missouri, along what came to be known as the Oregon Trail. Traveling alongside more than 100 wagons with 5,000 oxen and cattle, the settlers made the roughly 2,000-mile-long trip across six states seeking cheap land, better economic opportunities or adventure.

Thousands of emigrants followed in their footsteps each year until the first transcontinental railroad was completed in 1869, reducing the journey from months to days. In 1978, the historic route was designated a National Historic Trail by Congress. Today, visitors can still witness the deep wagon ruts and traces left behind by early American settlers along the Oregon Trail.