Westward expansion, particularly west of the Mississippi River, had profound effects on American politics. The Monroe Doctrine set forth a policy of Manifest Destiny that the United States should extend from the Atlantic Coast to the Pacific Coast. This expansion created a number of political crises that revolved around the expansion of slavery, dispossession of Native Americans and federal landholdings in the West.

Monroe Doctrine

In 1823, President James Monroe, in an address to Congress, outlined a foreign policy known as the Monroe Doctrine. In this address, Monroe stated that European powers were to stay out of Western Hemisphere affairs, and that the United States had the right to claim independent lands in the New World. A few decades later, American politicians used the Monroe Doctrine in conjunction with the policy of Manifest Destiny to justify expansion into the American West. Those who advocated Manifest Destiny believed that it was the right or “destiny” of the United States to span both the Atlantic and Pacific coasts.

Slavery

The spread of slavery into the West became the main political issue of the first half of the 19th century. To maintain a balance between free and slave states, a compromise was reached in 1820 in which Maine was admitted as a free state and Missouri as a slave state. The southern boundary of Missouri formed the 1820 Missouri Compromise line in which slavery would not be allowed north of this line, with the exception of Missouri. This issue came to a head after Texas was added as a slave state in 1845. This resulted in the Mexican-American War and the eventual addition of California as a free state to balance Texas. The political balance of power in Congress between free and slave states was precarious, and it came to a head with the passage of the Kansas-Nebraska Act in 1854. Although both states are north of the Missouri Compromise line, this act allowed Nebraska and Kansas to vote whether to be free or slave. Violence erupted in Kansas over these elections, and the Civil War began a few years later in 1861.

Native Americans

The American West was not empty land but rather inhabited by hundreds of various Native American groups. The forced removal of Native Americans from their lands for westward expansion is a tragic history. After the Louisiana Purchase in 1803, the United States began a policy of forced removal of tribes west of the Mississippi River. The policy became greatly enhanced during Andrew Jackson's presidency in 1830 with the passage of the Removal Act. The Removal Act enabled the federal government to remove Native Americans to lands west of the Mississippi River in exchange for lands east of the river, particularly in the south. This policy led to such tragedies as the infamous Trail of Tears during Cherokee removal. Once settlers began to move west of the Mississippi River, a reservation system was established, and Native Americans were restricted to lands apportioned them by the government.

Public Lands

Once lands the U.S. acquired lands either through treaties or forced removal, the president and congress then began policies directed at granting lands for settlers. In 1862, Lincoln signed the Homestead Act, which granted public lands in the West for settlement, particularly for agricultural or ranching purposes. As early as the 1830s, some like George Catlin, worried that far-reaching white settlement would destroy the wildlife, forests and Native American cultures of the West. As a result, some federal lands in the West became parks or preserves, such as Yosemite Park, which was donated to California as a state park in 1864. In 1872, the first national park was created at Yellowstone, and the National Park Service was created in 1916.