American Imperialism is the time period when America controlled countries that could survive on its own. This started when America was given Guam and puerto Rico, and Spain sold the Philippines to the USA for $20 million after the treaty of Paris. Then America annexed The Philippines making America an empire. This made people think that the people who were poorer than them were less evolved and more like an animal. This is what is called social Darwinism. This is also the cause racism, prejudice and hate for anyone who isn't like themselves.