The field of American Studies does not have a consensus citation style. When writing for a course assignment, consult your professor for guidance on selecting a style.
Professional scholars focusing on American Studies are typically required to adopt the citation style used by the publisher of their book or article. Descriptions for formatting both in-text and bibliography citations are typically given on an "Instructions for Authors" page on a journal publisher's website. For example, you can find the Author Guidelines page for The Journal of Popular Culture here.
In the absence of a required citation style, might consider using one of the widely used citation styles (i.e. Chicago, APA, MLA) described in detail on the Bates Library "Citing Sources" guide.