Manifest Destiny was the philosophy or belief that God had ordained Americans, specifically white Americans, to spread across the entire continent of North America, bringing with them capitalism and democracy. The term was first coined by a magazine editor named John L. O'Sullivan in the July-August 1845 issue of The Democratic Review.
Territorial expansion was facilitated by several agreements with foreign governments that enabled the United States to acquire vast areas of land. For instance, the Louisiana Purchase in 1803 almost doubled the size of the United States, giving it 828,000 square miles of land west of the Mississippi River. The Oregon Treaty of 1846 gave the United States present-day Washington, Oregon, Idaho, and parts of Wyoming and Montana. The Treaty of Guadalupe Hidalgo in 1848, which ended the Mexican-American War, gave the United States over 525,000 square miles more, comprising present-day California, Arizona, New Mexico, Colorado, Texas, Nevada, and Utah. The acquisition of all this territory along with belief in Manifest Destiny had a profound effect on numerous groups of people.
One of the groups affected by Manifest Destiny was lower and middle class white American farmers, tradesmen, and adventurers, who recognized the opportunity of acquiring a better life by settling on cheap land in the west. These were the people who were best poised to take advantage of the doctrine.
Manifest Destiny also profoundly affected the lives of Native Americans—but in a negative way. As settlers surged westward, many of them thought nothing of brutally mistreating and displacing Native Americans to take over their land. This ignited bloody wars between the Native Americans and the settlers. Native Americans ultimately lost and were relegated to reservations, usually on the worst patches of land.
Abolitionists, slave owners, and slaves were also affected by Manifest Destiny. Controversies erupted over whether acquired states and territories should allow or prohibit slavery. These disputes were not resolved until after the Civil War.
The rich were affected by Manifest Destiny. People made or increased fortunes by building railroads and shipping companies to unite the far-flung settlers and also by mining resources such as gold and silver.