The Panama Canal and the Roosevelt Corollary

President Theodore Roosevelt wanted a canal across Central America to link the Atlantic and Pacific for trade and naval power. When Colombia's senate rejected a canal treaty in 1903, Roosevelt supported a revolt in Panama, then part of Colombia; US warships prevented Colombian troops from suppressing it, and Panama declared independence on 3 November 1903. Within weeks the Hay–Bunau-Varilla Treaty gave the United States control of a canal zone, signed for Panama by a Frenchman with a financial interest in the project.

Building the canal required enormous effort, including mosquito control that sharply reduced yellow fever and malaria, and it opened on 15 August 1914. In 1904 Roosevelt also announced the Roosevelt Corollary to the Monroe Doctrine, claiming the right of the US to act as an 'international police power' in Latin America to prevent European intervention. Supporters saw stability and progress; critics in Latin America saw a new form of imperial control.