how and why did american imperialism develop in the 1800s and early 1900s?

American imperialism in the 1800s and early 1900s developed primarily due to economic interests, military strategy, and cultural beliefs. The United States sought new markets for its goods due to rapid industrialization after the Civil War, as the American frontier had closed by 1890, limiting continental expansion. This led to looking outward for new territories to control and trade with. Politically, the U.S. aimed to be the dominant power in the Western Hemisphere and compete with European powers who were dividing the world into colonies, especially in Africa and Asia. The motivations included economic desires for new markets and resources, political desires for global influence and military bases, geographic competition alongside European empires, and cultural beliefs in spreading Western ideals seen as superior, often framed as a humanitarian mission to civilize "backwards" peoples. Ideologies like Manifest Destiny and Social Darwinism also played roles in justifying expansion. American imperialism was partly a response to the growth of the U.S. economy and a desire to be recognized as a world power, emulating European colonial powers. This imperialism was characterized by a preference for strategic influence rather than just territorial conquest and was often presented as spreading American liberty and principles abroad, especially in conflicts like the Spanish-American War and the occupation of the Philippines.