The document discusses U.S. foreign policy and imperialism in the late 19th and early 20th centuries. It outlines the Monroe Doctrine of 1823 which opposed European colonization in the Western Hemisphere. It then discusses how under Presidents McKinley and Theodore Roosevelt from 1897-1909, U.S. imperialism increased as it acquired Cuba, Puerto Rico, and the Philippines and sought to protect economic interests through interventions backed by its growing navy. It also discusses Roosevelt's role in developing the Panama Canal to connect the Atlantic and Pacific oceans.