Mid Monongahela Valley History and Genealogy: http://freepages.genealogy.rootsweb.ancestry.com/~pamonval/
Counties of the Mid Mon Valley: Allegheny, Fayette, Greene, Washington and Westmoreland.
There were a LOT of Jacksons in Chester County. A study just of these Jacksons and their migrations would make a wonderful Special Project.
http://usgwarchives.org/pa/chester/ Scroll down for the Chester County Archives Index. A lot of good information here: Area History ~ Bibles ~ Bios ~ Cemetery ~ Tombtone Images ~ Census ~ Church ~ Court ~ Directories ~ Family History ~ Immigration ~ Land ~ Maps ~ Military ~ News ~ Obituaries ~ School ~ Tax ~ Vitals ~ Wills
Jackson DNA Project has a group just for the descendants of these Chester County Jacksons:
Chester County Pennsylvania Genealogy Project: http://chester.pa-roots.com/ Excellent site; wealth of information!
http://chester.pa-roots.com/biographies/jackson_isaac.html Bio & Will of Isaac Jackson of Chester Co.
Categories: Allegheny, Pennsylvania, United States | Chester, Pennsylvania, United States | Fayette, Pennsylvania, United States | Green, Pennsylvania, United States | Washington, Pennsylvania, United States | Westmoreland, Pennsylvania, United States | Surname in place | Pennsylvania, United States