1900-1913 - Progressive Era

The Open Door Policy was a U.S. policy announced by Secretary of State John Hay through diplomatic notes issued in 1899 and 1900. It promoted equal trade opportunities in China while calling on foreign powers to respect China’s Government authority and territory. Although foreign powers accepted its principles, the policy created no binding agreement and could not prevent nations from placing their own interests above China's.

The Roosevelt Corollary to the Monroe Doctrine was President Theodore Roosevelt’s policy toward Latin America and the Caribbean. Announced in December 1904, it claimed that the United States could intervene as a last resort when Western Hemisphere nations failed to meet international obligations or faced foreign aggression. The policy later justified United States intervention in Cuba, Nicaragua, Haiti, and the Dominican Republic.