Westward expansion trails

In the history of the United States, American pioneers built overland trails throughout the 19th century, especially between 1840 and 1847 as an alternative to sea and railroad transport. These settlers began to settle much of North America west of the Great Plains as part of the overland mass settlements of the mid-19th century. Settlers emigrating from the eastern United States did so with various motives, among them religious persecution and economic incentives, to move from their homes to destinations further west via routes such as the Oregon, California, and Mormon Trails. After the end of the Mexican–American War in 1848, vast new American conquests of territory again encouraged mass settlement. Legislations like the Donation Land Claim Act and significant events like the California Gold Rush further encouraged settlers to travel overland to the north.

Two major wagon-based transportation networks, one typically starting in Missouri and the other in the Mexican province of Santa Fe de Nuevo México, served the majority of settlers during the era of westward expansion. Three of the Missouri-based routes—the Oregon, California, and Mormon Trails—were collectively known as the Emigrant Trails. Historians have estimated at least 500,000 emigrants used these three trails between 1843 and 1869, and despite growing competition from transcontinental railroads, some use even continued into the early 20th century. The major southern routes were the Santa Fe, Southern Emigrant, and Old Spanish Trails, as well as its wagon road successor the Mormon Road, a southern spur of the California Trail used in the winter that also made use of the western half of the Old Spanish Trail. Regardless of the trail used, the journey was often slow and arduous, fraught with risks from dysentry, infectious diseases, dehydration, malnutrition, cholera, highwaymen, Indian raids, injury, and harsh weather, with as many as one in ten travelers dying along the way, usually as a result of disease.

The history of these trails and the settlers who traveled them have since become deeply embedded in the culture and folklore of the United States as some of the most significant influences to shape the content and character of the nation. The remains of many trail ruts can still be observed in various locations throughout the American West. Travelers may loosely follow various routes of the emigrant trails on modern highways through the use of byway signs across the western states.

Pioneers across what became the Western United States in the 19th century had the choice of several routes. Some of the earliest were those of the Mexicans in the southwest. American trade with Northern Mexico created the Santa Fe Trail between St. Louis and Santa Fe following an 18th-century route pioneered by the Spanish Empire. From Santa Fe, American traders followed the old El Camino Real de Tierra Adentro southward to Chihuahua by way of El Paso del Norte. The Old Spanish Trail from Santa Fe, in Mexican New Mexico Territory to Los Angeles, in Mexican Alta California, developed in 1829–1830 to support the trade of New Mexican wool products for California horses and mules and carried parties of fur traders and emigrants from New Mexico to Southern California.

Following the trails pioneered by fur traders, the Oregon Trail from Independence, Missouri to the Oregon Territory developed crossing the central Great Plains, Rocky Mountains and northern Great Basin. People followed this trail to take advantage of the fertile land the government gave out. Branching off from that route, some pioneers traveled southwestward on the California Trail from Fort Hall, Oregon Territory to Sutters Fort, in Mexican Alta California. Also branching off to the south was the Mormon Trail from Nauvoo, Illinois to Salt Lake City, Utah Territory. During the twenty-five years 1841–1866, 250,000 to 650,000 people "pulled up stakes," and headed west along these trails. About one-third immigrated to Oregon, one-third to California and one-third to Utah, Colorado, and Montana.

Although it is often stated that the Northern trails began in certain cities on the Missouri River, pioneers following any of the three trails typically left from one of three "jumping off" points on the Missouri's steamboat serviced river ports: Independence, Missouri, Saint Joseph, Missouri, or Council Bluffs, Iowa. Once known as Kanesville, Iowa until 1852; after river dredging in the early 1850s, the latter town at the Missouri-Platte confluence became the most common departure point since it was close in proximity to the River Platte—along which the eastern trails ascend to South Pass above Fort Laramie. The trails from these cities (and several others) converged in the mostly empty flatlands of central Nebraska near present-day Kearney, in the vicinity of Fort Kearney. From their confluence there the combined trails followed in succession the Platte, North Platte, and Sweetwater rivers westward across the full widths of Nebraska and Wyoming, and crossed the continental divide south of the Wind River Range through South Pass in southwestern Wyoming.

The most common vehicle for Oregon and California-bound pioneers was a covered wagon pulled by a team of oxen or mules (which were greatly preferred for their endurance and strength over horses) in the dry semi-arid terrain common to the high plains in the heat of summer. This heat could cause the wagons to catch on fire. People would form groups of wagons known as wagon trains. In later years, following the advice of Brigham Young, many Mormon emigrants made the crossing to Utah with handcarts. For all pioneers, the scarcity of potable water and fuel for fires was a common brutal challenge on the trip, which was exacerbated by the wide ranging temperature changes common to the mountain highlands and high plains, from 80 to 90 °F (27 to 32 °C) in the day to 40 °F (4 °C) at night. In many treeless areas, buffalo chips were the most common source of fuel.

During the Mexican–American War, the wagon to California road known as Cooke's Wagon Road, or Sonora Road, was built across Nuevo Mexico, Sonora and Alta California from Santa Fe, New Mexico to San Diego. It crossed what was then the northernmost part of Mexico. During the California Gold Rush the routes to California used were increased by the Siskiyou Trail from Oregon. In the south, the forty-niners used the Cooke Wagon Road, until some found a short cut, the Tucson Cutoff. This route, not closed to travel in winter, permitted travelers coming to New Mexico Territory on the Santa Fe Trail or on the San Antonio-El Paso Road developed in 1849, across West Texas to El Paso where it followed the El Camino Real de Tierra Adentro north to link up to the Cooke's Wagon Road/Southern Emigrant Trail at the cutoff through the San Diego Crossing. In 1856, as part of an improvement of the route as a military road, a cutoff was built to Cooke's Spring from Mesilla, (part of Mexico until 1853). From Cooke's Spring the road ran to the Yuma Crossing into California and on to Los Angeles. This route became the Southern Emigrant Trail. From Los Angeles the goldfields could be reached by land over the two routes north, the old El Camino Viejo or by what became the Stockton – Los Angeles Road. During the Gold Rush era it was these routes by which many herds of sheep and cattle were driven to California and the goldfields.