For years Americans followed a policy of isolationism—noninvolvement in world affairs. Following the Civil War, however, many wanted to expand trade with foreign nations and add territory to an American empire. While trade expanded to Japan and China, American influence also increased in Latin America. Some Americans had another reason for imperialist expansion. They believed that they had a mission to bring American religion and culture to the "uncivilized" peoples of Africa, Asia, and Latin America.
In 1898 the United States declared war on Spain. In the late 1800s Cubans had tried several times to win their independence from Spain, but each time Spain overpowered them and crushed the rebellion. Many Americans were sympathetic to the Cubans' struggle. President William McKinley sent the battleship Maine to protect American interests in Cuba. On the night of February 15, 1898, an explosion destroyed the Maine and took many American lives. American newspapers immediately blamed the Spanish, and on April 25, 1898, Congress declared war on Spain. The American military fought in Cuba and the Spanish colony of the Philippines. By August the war was over and the United States had acquired more territory.
With a growing empire and trade concerns in Asia, the United States saw the
need to build a canal across Central America. After supporting a revolution
in Panama the United States was able to negotiate with the new government for
a lease of ten miles of land across the center of the country. On August 15,
1914, the Panama Canal was opened to ships. Theodore Roosevelt's "big stick"
diplomacy, William Howard Taft's dollar diplomacy, and Woodrow Wilson's "moral diplomacy"
carried on the United States's policy of intervention in foreign countries.