Colorado Western Slope

The Western Slope is a colloquial term generally understood to describe the part of the state of Colorado west of the Continental Divide. Bodies of water west of the Divide flow toward the Pacific Ocean; water that falls and flows east of the Divide heads east toward the Gulf of Mexico. The Western Slope encompasses about 33% of the state, but has just 10% of the state's residents. The eastern part of the state, including the San Luis Valley and the Front Range, is the more populous portion of the state.

The Western Slope, though without an official definition, generally is understood to include Delta, Dolores, Eagle, Garfield, Grand, Gunnison, Hinsdale, La Plata, Mesa, Moffat, Montezuma, Montrose, Ouray, Pitkin, Rio Blanco, Routt, San Juan, San Miguel, and Summit counties and portions of Archuleta, Mineral, and Saguache counties.

The Western Slope has about 70% of the state's water.^{[clarification needed]} The Colorado River and its tributaries divide the region into north and south at Grand Junction, Colorado. The area has a climate similar to that of the Great Basin.

Paleo-Indians, early nomadic hunter-gatherers, followed large game throughout the Western Slope beginning about 12,000 BCE according to archaeological evidence found at the Mountaineer Archaeological Site near Gunnison, Colorado. Ancestral Puebloans inhabited the Gunnison and Colorado River basins between 6500 BCE and 200 CE. From about 350 BCE to 1300 CE, the Ancestral Puebloans lived in southwestern Colorado, including what is now Mesa Verde National Park. The Puebloans, while also continuing to hunt and gather food, were the first to farm and irrigate crops on the Western Slope. They left the area in the late 13th century, following a period of extensive drought.

The Ute people came to the Western Slope from the Great Basin and ranged through the area beginning about 1300. Their way of life, known as the Mountain Tradition, relied on hunting mule deer, elk, rabbits, and bison. They also gathered berries, roots, nuts and seeds. They frequented the area's hot springs, including the areas of Pagosa Springs, Glenwood Springs, and Steamboat Springs, Colorado. Many of the trails established by the Utes became routes for roads, stage lines, highways, and railways.

Spanish explorers visited the Western Slope in the 18th century. Juan de Rivera explored the area in 1765, followed in 1776 by the Domínguez–Escalante expedition. Fur trappers, also called mountain men, of European descent entered the area to trap beaver for their furs. Trading posts were established on the Western Slope beginning in 1828 with the Fort Uncompahgre and Fort Davy Crockett at the center for trapping furs at Brown's Hole. The trading posts were used to trade furs for supplies or goods. Trappers and explorers include Kit Carson and Jim Bridger. They and others guided John C. Frémont (1843–53), John W. Gunnison (1853), and John Wesley Powell (1869) on their expeditions into the Western Slope. Once the demand for beaver furs declined and beaver had been over-trapped, the fur trade was greatly diminished.

In 1858 and 1859, the Gold Rush into Colorado brought miners into the region and mining towns like Breckenridge. Mining districts were established in the San Juan Mountains, Gunnison River Valley, Sawatch Mountains and Elk Mountains. The initial interest was panning for gold in rivers and that grew over the decades to including mining for ore, coal, and fuel below ground. Many mining towns were established in the Western Slope. Ferdinand Vandeveer Hayden's expedition of 1872 to 1873 resulted in maps of the Western Slope that were later used by investors, mining engineers, railroad owners, and others leading the western expansion into western Colorado.

After contact with people of European descent, there were a number of treaties to define boundaries for Native Americans, including the Treaty of 1868 that resulted in the Utes relinquishing their land east of the Continental Divide. They maintained most of their land in the Western Slope with the treaty. The Utes were pushed out of much of the Western Slope after gold was found in the San Juan Mountains, including through the Brunot Agreement. Utes were removed from the state after the Meeker Massacre of 1879. A reservation was created in Utah for the tribes that participated in the massacre. The Southern and Ute Mountain Utes have land in southern Colorado, the Southern Ute Indian Reservation and the Ute Mountain Ute Tribe Reservation.