Settlement

After 1802, American fur traders and explorers ushered in the first widespread Caucasian presence in the Rockies south of the 49th parallel. The more famous of these include Americans William Henry Ashley, Jim Bridger, Kit Carson, John Colter, Thomas Fitzpatrick, Andrew Henry, and Jedediah Smith. On July 24, 1832, Benjamin Bonneville led the first wagon train across the Rocky Mountains by using South Pass in the present State of Wyoming. Similarly, in the wake of Mackenzie's 1793 expedition, fur trading posts were established west of the Northern Rockies in a region of the northern Interior Plateau of British Columbia which came to be known as New Caledonia, beginning with Fort McLeod (today's community of McLeod Lake) and Fort Fraser, but ultimately focused on Stuart Lake Post (today's Fort St. James).

Negotiations between the United Kingdom and the United States over the next few decades failed to settle upon a compromise boundary and the Oregon Dispute became important in geopolitical diplomacy between the British Empire and the new American Republic. In 1841 James Sinclair, Chief Factor of the Hudson's Bay Company, guided some 200 settlers from the Red River Colony west to bolster settlement around Fort Vancouver in an attempt to retain the Columbia District for Britain. The party crossed the Rockies into the Columbia Valley, a region of the Rocky Mountain Trench near present-day Radium Hot Springs, British Columbia, then traveled south. Despite such efforts, in 1846, Britain ceded all claim to Columbia District lands south of the 49th parallel to the United States; as resolution to the Oregon boundary dispute by the Oregon Treaty.

Cherokee Trail near Fort Collins, Colorado, from a sketch taken 7 June 1859.

Thousands passed through the Rocky Mountains on the Oregon Trail beginning in the 1840s. The Mormons began to settle near the Great Salt Lake in 1847. From 1859 to 1864, gold was discovered in Colorado, Idaho, Montana, and British Columbia, sparking several gold rushes bringing thousands of prospectors and miners to explore every mountain and canyon and to create the Rocky Mountains' first major industry. The Idaho gold rush alone produced more gold than the California and Alaska gold rushes combined and was important in the financing of the Union Army during the American Civil War. The transcontinental railroad was completed in 1869, and Yellowstone National Park was established as the world's first national park in 1872. Meanwhile, a transcontinental railroad in Canada was originally promised in 1871. Though political complications pushed its completion to 1885, the Canadian Pacific Railway eventually followed the Kicking Horse and Rogers Passes to the Pacific Ocean. Canadian railway officials also convinced Parliament to set aside vast areas of the Canadian Rockies as Jasper, Banff, Yoho, and Waterton Lakes National Parks, laying the foundation for a tourism industry which thrives to this day. Glacier National Park (MT) was established with a similar relationship to tourism promotions by the Great Northern Railway. While settlers filled the valleys and mining towns, conservation and preservation ethics began to take hold. U.S. President Harrison established several forest reserves in the Rocky Mountains in 1891–92. In 1905, U.S. President Theodore Roosevelt extended the Medicine Bow Forest Reserve to include the area now managed as Rocky Mountain National Park. Economic development began to center on mining, forestry, agriculture, and recreation, as well as on the service industries that support them. Tents and camps became ranches and farms, forts and train stations became towns, and some towns became cities.