Your early-settler ancestor may have lived in several different counties even if he didn't move an inch. Here's how to figure out those shifting county boundaries and tell which county has the genealogy records you need.
As the population increased in the places your ancestors settled, counties were often subdivided, renamed and rearranged—potentially wreaking havoc with your knowledge of where to look for records.
Records generally stayed in the county where they were created. Let’s say your ancestor’s land purchase in Washington County is registered at the courthouse in the county seat of Springfield. Two years later, Washington County is carved up into three smaller counties. Your ancestor’s new county is Jefferson County, with Pleasantville as the county seat. The deed for his land purchase will remain in the courthouse in Springfield. If he sells the land, though, the transaction will be recorded in Pleasantville.