Bradford W. Wright's Comic Book Nation (2003) is one of the few truly academic resources regarding comic books' socially reflective and historic place in American society. In each chapter, Wright places the genres and common themes of each period in comics' history in political-socio-historic context, providing a clear observations of how the ethos of each generation living through those times affected, and sometimes was affected by the content of comic books.
Wright also spends a decent amount of time dissecting Dr. Frederic Wertham and his 1954, 400-page, "scientific study," Seduction of the Innocent, in which the psychologist attempts to link most comics books to juvenile delinquency. Wright finds much fault in Wertham's methods, but not in the doctor's caring about the lives of youths, presenting Wertham, not as a villain, but as a really misguided champion for the children.
There are countless endnotes providing readers with knowledge of, if not easy accessibility to, all of Wright's resources from his research.
I highly recommend this book for anyone interested in the study of comic books and their history within the United States.
Book cover borrowed from Google Books, though this book is likely available through your local independent book retailer.