Focus is on western Pennsylvania. Very short on general history, but that's OK since other sources cover that topic well. This version runs 774 pages and includes a workable index of names. It consists mostly of an extensive genealogy list of families that lived, at least for a while, in the south-western portions of Pennsylvania. There is a short introduction for many of the families, running from a paragraph to perhaps a few pages. These family histories contain details not likely to be found elsewhere.