American Century is a characterization of the period since the middle of the 20th century as being largely dominated by the United States in political, economic, and cultural terms. It is comparable to the description of the period 1815–1914 as Britain's Imperial Century. Critical to the American Century was US control of the world's oil resources. The United States' influence grew throughout the 20th century, but became especially dominant after the end of World War II, when only two superpowers remained, the United States and the Soviet Union. After the dissolution of the Soviet Union in 1991, the United States remained the world's only superpower, and became the hegemon, or what some have termed a hyperpower.