Final answer:
Economic interest, ideology, and strategic interest were the main causes of American imperialism. Economic interest drove the need for access to international markets and raw materials. Ideological factors like American exceptionalism and the desire to spread democracy also influenced imperialism.
Step-by-step explanation:
In encouraging American imperialism, there were three main causes to consider: economic interest, ideology, and strategic interest. Economic interest played a significant role in driving American imperialism during the 19th century. As the United States underwent industrialization, business owners sought access to international markets for exports and raw materials. Ideological factors, such as American exceptionalism and the belief in spreading democracy, also influenced American imperialism. Finally, strategic interest played a role as well, as the United States aimed to counterbalance the economic strength of other imperial powers.