The document provides background information on how the US became a world power following the Civil War. It discusses the US policy of isolationism in the late 1800s while European nations practiced imperialism and colonialism. Economic pressures and social ideologies influenced the US to begin expanding overseas through acquiring Hawaii and building a modern navy. Tensions grew between the US and Spain over Cuba, which led to the Spanish-American War in 1898 and marked the US emerging as a new imperial power.