How did US expand in the early 1800s?

In the early 1800s, the United States expanded its territory primarily through a combination of purchases, treaties, and military conflicts. Key events included the Louisiana Purchase in 1803, which doubled the nation's size, and the annexation of Texas in 1845. The U.S. also engaged in the Mexican-American War (1846-1848), resulting in significant land gains including present-day California, Arizona, New Mexico, and other territories. This expansion was driven by the ideology of Manifest Destiny, the belief that the U.S. was destined to expand across the continent.