In the 19th century, the term "Manifest Destiny" referred to the belief that the expansion of the United States across the American continent was both justified and inevitable. This ideology was rooted in the notion that Americans were destined to spread democracy and capitalism, viewed as a divine right and duty. Manifest Destiny motivated the westward expansion, including the acquisition of territories like Texas and California. It played a significant role in motivating policies such as the Indian Removal Act of 1830 and the Mexican-American War. Critics of the concept argued it led to imperialism and the displacement of Native American peoples.