County Boundary Changes–Newberry Library
The Newberry Library has a website, Atlas of Historical County Boundaries, http://publications.newberry.org/ahcbp/, which has maps and detailed bibliographic information on county boundary changes.
Might be worth a look.
© Michael John Neill, “Genealogy Tip of the Day,” http://genealogytipoftheday.blogspot.com, 28-May-2012.