What term describes the movement of American settlers toward the West?

The term "American Expansionism" accurately describes the movement of American settlers toward the West during the 19th century. This concept refers to the policy and ideology advocating for the expansion of the United States across the North American continent. This period was marked by significant migration, driven by factors such as economic opportunities, land availability, and the belief in America's destined growth.

The term encapsulates not only the physical movement of people but also the broader political and social motivations behind expansion, reflecting a nationalistic spirit that characterized much of U.S. history during this time. American Expansionism is closely associated with various historical events, such as the Louisiana Purchase, the annexation of Texas, and the acquisition of territories following the Mexican-American War.

The other options, while related to the theme of expansion, do not capture the full scope of the ideological basis that drove American settlers West in the same way that "American Expansionism" does. For instance, "Manifest Destiny" specifically refers to a belief that provoked American expansion but does not encompass the broader notion of expansionism itself. "Desire for expansion" lacks the historical context and specific connotations tied to U.S. history, and "Frontier Development" speaks more to the social and economic growth