- Puerto Rico, Guam and the Philippines became territories of the United States resulting from the Treaty of Paris (1898).
- Cuba: The Teller Amendment promised Cuban independence, which was granted in 1902 (the Platt Amendment granted the US control over Cuba's foreign relations and allowed for the US to intervene if necessary to restore order).
- The United States emerged as a world power. Its victory over Spain demonstrated its military strength and its ability to project power overseas.
- Imperialism: The acquisition of overseas territories fueled a debate over the role of the United States as an imperial power. Some Americans believed that the United States should expand its empire, while others argued that it should focus on its own domestic development.
- Anti-imperialism: was a movement opposed to the annexation of the Philippines. Its leaders argued that it was immoral for the United States to take over another country against the will of its people and that it would be difficult and expensive to govern a colony so far away. They felt that the acquisition of the Philippines would lead to a more militarized and interventionist foreign policy.