How did the US expand its territory across the continent?

The U.S. expanded its territory across the continent 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 following its independence from Mexico. The concept of Manifest Destiny also fueled westward expansion, leading to conflicts such as the Mexican-American War, which resulted in significant territorial gains. Additionally, the U.S. acquired land through treaties with Native American tribes, often under coercive circumstances.