Go to the 'Back of the Book'!
The early local mail services, the Civil War, the myriad of taxes, the variety of postal services & growing influence overseas meant that a fascinating array of adhesives, both postal & otherwise have been produced by the United States of America. Most appear in the back of the Scott Specialized Catalogue (hence the term "back of the book" applied by many collectors to this area of philately).
General
General
General