Latter-day Saints began evacuating Nauvoo, Illinois, crossing the frozen Mississippi River into Iowa and starting the multi-year overland migration that would culminate in settlement in the Great Basin.
About 450 men assembled near Mosquito Creek (Council Bluffs area) as part of the recruitment and mustering of the Mormon Battalion, which would march west as a U.S. Army unit during the Mexican–American War.
Brigham Young and the first pioneer company entered the Salt Lake Valley, marking the beginning of sustained Latter-day Saint settlement in the Great Basin (commemorated as Utah’s Pioneer Day).
Settlers drafted and adopted a constitution for the proposed State of Deseret, seeking U.S. recognition and establishing a provisional civil framework for the Great Basin settlements.
Mormon militia forces attacked and killed scores of Timpanogos people near Utah Lake in a violent episode tied to early settler–Indigenous conflict during Utah’s initial colonization period.
Congress passed the Utah Organic Act, creating Utah Territory and replacing the settlers’ proposed State of Deseret with a federally recognized territorial government.
At a special conference in the Salt Lake Tabernacle, Orson Pratt (with Brigham Young) publicly announced and defended plural marriage, making a previously secret practice an official, public doctrine within the LDS community.
The LDS handcart system began as a cost-saving migration method; the first handcart company arrived in Salt Lake City, demonstrating the viability—though risks—of the approach for poorer emigrants.
President James Buchanan declared Utah in rebellion and mobilized troops to install a new territorial governor, escalating a confrontation over federal authority and Mormon governance in the territory.
In southern Utah, members of the Baker–Fancher emigrant party were attacked and ultimately killed in a massacre involving local Mormon militia and Paiute auxiliaries; the event became a lasting flashpoint in regional and LDS history.
President Abraham Lincoln signed federal legislation banning bigamy in U.S. territories, initiating a long legal and political conflict between the federal government and Utah’s LDS-led society over plural marriage and church power.
The Union Pacific and Central Pacific lines were ceremonially joined at Promontory Summit, dramatically reshaping migration and supply networks to Utah and accelerating non-Mormon immigration and economic integration.
Utah Territory granted women the right to vote, making Utah a national early adopter of women’s suffrage and embedding voting rights within local political and religious debates of the era.
The U.S. Supreme Court ruled that religious belief does not exempt individuals from laws criminalizing polygamy, strengthening federal enforcement efforts against plural marriage in Utah Territory.
Congress expanded federal power in Utah by criminalizing “unlawful cohabitation” and restricting civil rights (including voting and jury service) for those involved, intensifying pressure on LDS communities.
Congress further escalated enforcement by disincorporating the LDS Church and enabling seizure of its assets, sharply constraining church institutions and territorial politics.
Church President Wilford Woodruff issued the 1890 Manifesto, formally advising against new plural marriages; it marked a turning point in the relationship between the LDS Church, federal authority, and Utah’s path toward statehood.
Mormon Migration and the Settlement of Utah (1846–1890)
