It was primarily the "B. Young American" movement that was in favor of U.S. expansion in Latin America, although it should be noted that there were others who were in favor of such expansionism as well.
Give me that brain first ;)
Well, after the ending of American Civil War it mean that a lot of cotton exports from America were available once more. There was also a competition in the global market, to supply cotton and that's why it helped keep down the price after 1865
