The Columbia Guide to American Environmental History

This chapter focuses on the westward movement of Americans, including the settlement of California and the Great Plains, as examples of the interactive relationships between the environment and humanity in the western United States. Core ideas—such as the frontier and Manifest Destiny—helped to shape the ways in which land was acquired and developed.This chapter explores the multicultural relationships, opportunities, and oppression experienced by the many ethnic groups that developed California during the Gold Rush, and examines the environmental effects of gold mining. It looks at the subsequent settlement of the Great Plains and the impact of various technologies on the transformation of the Plains environment. Finally, it offers some theories put forward by environmental historians as to why the West developed as it did.

The western United States was acquired in several stages during the first half of the nineteenth century. The Louisiana Purchase in 1803, which extended westward from the Mississippi River to the Continental Divide, had inspired President Thomas Jefferson to send Merriwether Lewis and William Clark to explore the Mississippi and the Missouri Rivers. They crossed the mountains in Idaho and followed the Columbia River to the Pacific. Following their successful return, numerous expeditions were mounted by fur traders and explorers into the Rocky, Sierra Nevada, and Cascade Mountains. By the 1840s, most of the land west of the Mississippi had been explored, and wagon trains of settlers were following the Oregon Trail westward to Oregon's Willamette Valley, just south of the Columbia River. President James K. Polk envisioned the United States as extending

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