How did the idea of manifest destiny help push the expansion of the US into oregoncalifornia and the former Mexican territories?

Manifest Destiny was the 19th-century belief that the United States was destined to expand across the North American continent, which fueled the push into Oregon, California, and former Mexican territories. This ideology justified the westward expansion as a divine right and a mission to spread democracy and civilization. It encouraged settlers to move westward, leading to conflicts with Native American tribes and Mexico, ultimately resulting in significant territorial gains for the U.S. through treaties and military actions.