Final answer:
The belief that the United States was fated to expand across North America was known as Manifest Destiny, a term that emerged in the 1840s. This doctrine held that Americans were destined to spread their democratic institutions across the continent, a process justified as inevitable, just, and divinely ordained, leading to the expansion of the U.S. territory.
Step-by-step explanation:
The belief that it was the fate of the U.S. to expand was called Manifest Destiny. This concept, which appeared during the 1840s, provided religious and cultural justifications for American territorial expansion. Under the Manifest Destiny doctrine.
it was believed that the United States was destined to expand its democratic institutions and political control 'from sea to shining sea', Americanizing the inhabitants of North America, including native tribes and Mexicans, in the process. Expansionists viewed this as not only inevitable and just but also as a divine right.
The term 'Manifest Destiny' was coined by John O'Sullivan in 1845 when he asserted that it was the United States' obvious fate to spread over the continent. This belief played a significant role in the expansionist policies of the era, leading to the addition of Texas and Oregon to the Union and was a factor leading to the Mexican-American War, which resulted in the U.S. acquiring territories in the Southwest, including California.