Growth in U.S. economy increased demand for (and value of) farmland, ranches, and furs; the cotton gin increased the area in which cotton could be grown profitably; the discovery of gold in California attracted 80,000 people in1849. Cheap land so that families could farm for themselves.

Manifest Destiny, a phrase coined in 1845, is the idea that the United States is destined—by God, its advocates believed—to expand its dominion and spread democracy and capitalism across the entire North American continent.

Manifest Destiny. Manifest Destiny is the belief that Americans had the right, or even the duty, to expand westward across the North American continent from the Atlantic Ocean to the Pacific Ocean. This would spread the glorious institutions of civilization and democracy to the barbaric Native Americans.

During this crucial period, the United States pursued a policy of expansion based on “manifest destiny,” the ideology that Americans were in fact destined to extend their nation across the continent. The United States even proved to be willing to go to war to secure new territories.

The ideology of Manifest Destiny inspired a variety of measures designed to remove or destroy the native population. US President James K. Polk (1845-1849) is the leader most associated with Manifest Destiny. Manifest Destiny inflamed sectional tensions over slavery, which ultimately led to the Civil War.

Before the American Civil War the idea of Manifest Destiny was used to validate continental acquisitions in the Oregon Country, Texas, New Mexico, and California. Later it was used to justify the purchase of Alaska and annexation of Hawaii.

With its triumph in the Mexican-American War, the United States seemingly realized its Manifest Destiny by gaining an immense domain (more than 525,000 square miles [1,360,000 square km] of land), including present-day Arizona, California, western Colorado, Nevada, New Mexico, Texas, and Utah.