Between 1800 and 1870, nearly half a million Americans set out across the frontier on the many trails that led west from settled America. Whether they took the Santa Fe Trail, the Oregon-California Trail, the Mormon Trail, or one of many others, these trappers, traders, farmers, and families set out on a journey of discovery. Lured by promises—of gold, of lucrative trade, or of fertile farmland—these pioneers endured weeks and even months of arduous travel across vast plains and arid deserts and over high mountain passes to reach their destination and build the communities that defined the American West. The trails they blazed helped pave the way for the civilizing of the West.

The First Expeditions

Until the Louisiana Purchase of 1803 (see Chapter 1), the western boundary of the United States was the Mississippi River. Mere political boundaries had never stopped trappers and traders from traveling beyond...