A great source for information on archaeological sites and cultures, particularly during the last few centuries, is the local historical society museum and library. You may find a display of artifacts from a government-sponsored excavation completed during the Works Project Administration days of the 1930s; or a display of artifacts that are part of a museum exchange project.
You might find books and memoirs of local residents about the history of the area, or even, best of all, a librarian with a voluminous memory. Joe Ryan at Syracuse has assembled a very useful list of all the US historical societies and archives.
