What belief held that the United States had the right and duty to expand throughout North America?

The belief that the United States had the right and duty to expand throughout North America is known as Manifest Destiny. This ideology emerged in the 19th century and was rooted in the idea that Americans were destined, by God or fate, to spread their democratic and cultural values across the continent. It justified territorial expansion, leading to events such as the annexation of Texas and the acquisition of lands following the Mexican-American War. Manifest Destiny was significant in shaping U.S. policies and attitudes toward expansion, often overlooking the rights and sovereignty of Indigenous peoples and other nations.

American Exceptionalism refers to the belief that the U.S. has a unique mission to spread democracy and maintain a special role in the world, but it doesn't specifically address territorial expansion. Cultural Imperialism describes the idea of promoting one culture over another, which is related but distinct from the specific notion of territorial expansion held by Manifest Destiny. Frontierism emphasizes the experiences and lifestyles of settlers on the frontier but does not encapsulate the broader ideological framework of U.S. expansionism described in Manifest Destiny.