The Whaling Industry allowed for Americans to dissolve isolation of Asian countries. The Treaty of Guadalupe Hidalgo added ports along the Pacific that wereused for U.S. influence and explorations. Opium was also a major driving factor ofinterest through trade, in addition to the idea of expansion with the Kanagawa Treaty,which opened ports to American commerce. The United States wanted to extend theirborders to keep close contact for American success.
Immigration. The song's other title was "They're coming to America", it's a song about american dream, and opportunities which america gives.
I guess it was president andrew jhonson who offered resistance to reconstruction