This an a pretty broad question and I am sure that you will get many different answers. Here are a few values that I think has been important to America over the years. First, I believe that there is a strong emphasis on freedom; it is everywhere. Second, there is the closely related idea of democracy. Third, self-reliance is an important value that has been emphasized in the past, but I think it is still with us today. Fourth, one of the defining values of the US definitely is individualism. Fifth, I would say materialism or the desire to gain wealth is another defining character. Finally, there is an sense of American exceptionalism.
Leadership...it's an acronym