Here is a short bibliography of some of the background books I'm finding useful while preparing the Free Family history. You may want to read along. I've marked the most useful, from a research perspective, with an asterisk.
Baldwin, Carl R. Echoes of Their Voices: A Saga of the Pioneers Who Pushed the Frontier Westward to the Mississippi. St Louis, MO: Hawthorn Publishing Company, Inc. 1978. Though this book does not discuss the Frees themselves, it describes the lives and circumstances of the Illinois frontiersmen when the Frees arrived.
Everton, A. Lee et al. *The Handy Book for Genealogists. Logan, UT: Everton Publishers, Inc. 1999. The Handybook is essential for finding county records.
Fischer, David Hackett. *Albion's Seed: Four British Folkways in America. New York: Oxford University Press.1989. It is my opinion that colonial American research should not be done without this book.
Horwitz, Tony. A Voyage Long and Strange: On the Trail of Vikings, Conquistadors, Lost Colonists, and Other Adventurers in Early America. Containing very readable "new" history, Horwtiz' book is fundamental to basic colonial history.
Johnston, George. History of Cecil County, Maryland and the Early Settlements around the Head of the Chesapeake Bay and on the Delaware River with Sketches of Some of the Old Families of Cecil County. Philadelphia: Dickson and Gilling. 1881.
O'Brien, Greg. Chronology of Native Americans: The Ultimate Guide to North America's Indigenous Peoples. London: Amber Books Ltd. 2011. This book contains a job description of an Indian Fur Trader and clarifies the colonial economy as well as the Indian wars.
Ramsey, Robert W. Carolina Cradle: Settlement of the Northwest Carolina Frontier, 1747-1762. Chapel Hill, NC: The University of North Carolina Press. 1964. Reprint. Chapter 3 includes Sherrills.
Schaefer, Christina K. *Genealogical Encyclopedia of the Colonial Americas. Baltimore, MD: Genealogical Publishing Co., Inc. 1998. While listing primarily sources found at the Family History Library, this book is beyond useful for finding aids.
Sherrill, William Andrew. Captain William Sherrill Son of Adam and Elizabeth and Some of Their Descendants. Decorah, IA: The Anundsen Publishing Co. 1979. This book represents a colossal effort on the part of Bill Anderson and other Sherrill researchers to document one of our ancestors, Captain William Sherrill, and his family. A book has been planned for each of Adam Sherrill's sons. This book and at least one other about Jacob have been completed.
Trager, James. *The People's Chronology: A Year-by-Year Record of Human Events from Prehistory to the Present. New York: Henry Holt and Co. 1994. The timeline contained in these many pages makes history more accurate.
As you can imagine, I've got books piled all over the place. Several of the books mentioned above are just great reads including those by O'Brien, Horwitz and Fischer. Enjoy!