Utah's historic Indian groups are primarily Shoshonean: the Ute in the eastern two-thirds of the state, the Goshute of the western desert, and the Southern Paiute of southwestern Utah. The Athapaskan-speaking Navaho of southeastern Utah migrated from western Canada, arriving not long before the Spaniards. The differing lifestyles of each group remained essentially unchanged until the introduction of the horse by the Spanish sometime after 1600. White settlement from 1847 led to two wars between whites and Indians-the Walker War of 1853–54 and the even more costly Black Hawk War of 1865–68-resulting finally in the removal of many Indians to reservations.

Mexicans and Spaniards are the first non-Indians known to have entered Utah, with Juan María Antonio Rivera reportedly arriving near present-day Moab as early as 1765. In July 1776, a party led by two Franciscan priests, Francisco Atanasio Domínguez and Silvestre Vélez de Escalanta, entered Utah from the east, traversed the Uinta basin, crossed the Wasatch Mountains, and visited the Ute encampment at Utah Lake. Trade between Santa Fe, the capital of the Spanish province of New Mexico, and the Indians of Utah was fairly well established by the early 1800s.

Until 1848, the 1,200-mi (1,900-km) Spanish Trail, the longest segment of which lies in Utah, was the main route through the Southwest. Following this trail, mountain men competing for fur explored vast areas of the American West, including most of Utah's rivers and valleys. In the 1840s, Utah was traversed by California-bound settlers and explorers, the most notable being John C. Frémont.

When Joseph Smith, Jr., founder of the Church of Jesus Christ of Latter-day Saints (Mormons), was lynched at Carthage, Ill., in June 1844, Brigham Young and other Mormon leaders decided to move west. By April 1847, the pioneer company of Mormons, including three blacks, was on its way to Utah, the reports of Frémont having influenced their choice of the Great Basin as a refuge. Advance scouts entered the Salt Lake Valley on 22 July, and the rest of the company two days later. Planting and irrigation were begun immediately. Natural resources were regarded as community property, and the church organization served as the first government.

After the Treaty of Guadalupe-Hidalgo (1848) gave the US title to much of the Southwest, the Mormons established the provisional state of Deseret. Congress refused to admit Deseret to the Union, choosing instead to create Utah Territory "with or without slavery." The territory encompassed, in addition to present-day Utah, most of Nevada and parts of Wyoming and Colorado; land cessions during the 1860s left Utah with its present boundaries.

The territorial period lasted for 46 years, marked by immigration, growth, and conflict. Reports that Utahns were in rebellion against federal authority led President James Buchanan to send an expeditionary force under Albert Sidney Johnston to Utah in 1857. On 11 September, Mormon militiamen and their Indian allies, caught up in an atmosphere of war hysteria, massacred some 120 California-bound migrants at Mountain Meadows—the darkest event in Utah history and the only major disaster of the so—called Utah War. Peace was attained in June 1858, and Alfred Cumming assumed civil authority, replacing Brigham Young as territorial governor. Cumming's appointment signaled the beginning of prolonged hostility between Mormon leaders and federal authorities.

Almost 98% of Utah's total population was Mormon until after 1870, and the Mormon way of life dominated politics, economics, and social and cultural activities. As church president, Brigham Young remained the principal figure in the territory until his death in 1877. He contracted in 1868 with the Union Pacific to lay part of the track for the transcontinental railroad in Utah, and on 10 May 1869, the Central (now Southern) Pacific and Union Pacific were joined at Promontory. During the 1870s, new rail lines connected many settlements with the capital, Salt Lake City, spurring commerce and mining. Young had discouraged mining until agriculture and manufacturing were firmly established. Not until 1863, with the rediscovery of silver-bearing ore in Bingham Canyon, did the boom in precious metals begin. Those connected with mining, mostly non-Mormons, began to exert influence in the territory's business, politics, and social life.

Several factors made the non-Mormon minority fearful of Mormon domination: communitarian economic practices, lack of free public schools, encouragement of immigration of Mormon converts, church authoritarianism, and the mingling of church and state. But the most sensational reason was the Mormon practice of polygamy. Congress passed the Anti-Bigamy Act in 1862, but it was generally not enforced. After the Edmunds Act of 1882 was upheld by the US Supreme Court, arrests for polygamy greatly increased. Finally, in 1887, the Edmunds-Tucker Act dissolved the Mormon Church as a corporate entity, thereby threatening the survival of all Mormon institutions.

In fall 1890, Mormon president Wilford Woodruff issued a manifesto renouncing the practice of polygamy. The following year, the Republican and Democratic parties were organized in Utah, effectively ending political division along religious lines. A constitutional convention was held in 1895, and statehood became a reality on 4 January 1896. The new state constitution provided for an elected governor and a bicameral legislature, and restored the franchise to women, a privilege they had enjoyed from 1870 until 1887, when the Edmunds-Tucker Act had disfranchised Utah women and polygamous men.

The early 20th century saw further growth of the mineral industry. Many of those who came to mine copper and coal were foreign immigrants. Militant union activity had begun slowly during the 1890s, until an explosion that killed 200 miners at Scofield on 1 May 1900 dramatized the plight of the miners and galvanized radical organizers in the state. It was in Utah in 1915 that a Swedish miner and songwriter named Joe Hill, associated with the Industrial Workers of the World ("Wobblies"), was executed for the murder of a Salt Lake City grocer and his son, a case that continues to generate controversy because of the circumstantial quality of the evidence against him.

Gradually, modern cities emerged, along with power plants, interurban railroads, and highways. By 1920, nearly half the population lived along the Wasatch Front. The influx of various ethnic groups diversified the state's social and cultural life, and the proportion of Mormons in the total population declined to about 68% in 1920.

Utah businesses enjoyed the postwar prosperity of the 1920s. On the other hand, mining and agriculture were depressed throughout the 1920s and 1930s, decades marked by increased union activity, particularly in the coal and copper industries. The depression of the 1930s hit Utah especially hard. Severe droughts hurt farmers in 1931 and 1934, and high freight rates limited the expansion of manufacturing. With the coming of World War II, increased demand for food revived Utah's agriculture, and important military installations and war-related industries brought new jobs to the state.

In the years since World War II, the state's population has more than doubled, while per capita income has declined relative to the national average-both trends indicative of a very high birthrate. Politics generally reflect prevailing Mormon attitudes and tend to be conservative. The state successfully opposed plans for storing nerve gas bombs in Utah and for the location in the western desert of an MX missile racetrack system. In 1967 work began on the Central Utah Project, a dam and irrigation program still under way in the early 2000s and intended to assure an adequate water supply for the state through the year 2020.

Utah had one of the nation's fastest growing economies in the 1990s and one of its lowest rates of unemployment. The state's leading industry was the manufacture of transport equipment, including aircraft parts and parts for missiles and rockets. At the beginning of the 21st century, Utahns were divided over the issue of protecting the state's natural areas from residential and commercial development.

Salt Lake City was the site of the 2002 Winter Olympic Games. The selection of Salt Lake City as the site for the games was controversial and mired in a scandal that broke in 1998, as bid leaders for Salt Lake City's selection were charged with bribing International Olympic Committee officials in exchange for their support of Salt Lake City's bid. Ten International Olympic Committee members either resigned or were expelled as a result of the scandal. The 2002 Winter Olympics generated $56 million in profits.

Governor Michael O. Leavitt became the second Utah governor to be elected to a third term in 2000, but as of mid-2003, he had not yet announced if he would run for an unprecedented fourth term. He was responsible for cutting income and property taxes, and in 2003, pledged to balance Utah's budget without raising taxes. In 2003, Leavitt maintained economic prosperity would be achieved through reforming Utah's education system, including adopting a competency standard for high school graduation. Wildfires and serious drought conditions plagued Utah in the early 2000s.