Which term describes the idea that the United States was destined to expand its territory across North America?

The concept that describes the belief that the United States was destined to expand its territory across North America is referred to as Manifest Destiny. This term emerged in the 19th century and encapsulated the idea that it was both justified and inevitable for the United States to extend its dominion and spread democracy and capitalism across the continent. Supporters of Manifest Destiny viewed this expansion as a divine right and a national mission, seeing the movement westward not only as a chance for growth but also as a means of fulfilling a higher purpose.

The other terms, while related to American history, do not accurately capture this specific ideology. Expansionism generally refers to the broader policy of territorial or economic expansion but does not encapsulate the belief system that underpinned the movement as thoroughly as Manifest Destiny does. Nativism pertains to favoring the interests of native inhabitants over immigrants, which is a different social and political issue. On the other hand, Domino Theory is a geopolitical theory concerning the spread of communism during the Cold War, adding a layer of complexity unrelated to territorial expansionist ideals during the 19th century.