The subject matter of course is Americana. According to Wiki this would be defined as: Americana refers to artifacts, or a collection of artifacts, related to the history, geography, folklore and cultural heritage of the United States.
Please submit your view or idea imagery-wise on what you think could be Americana. Think: History, Folklore, Myths, and of course Apple Pie. Everything goes. That is if it tells a story about the US and its culture making this country unique.