One of the common brick walls that we come across when doing our genealogy research it not locating families where we thought they would be. Making certain that you know the boundaries of the jurisdiction where your family often sheds light on boundary changes that we were not aware of previously.
Our ancestors would live in the same location their whole lives, but their geographic area would fall under different jurisdictions. Here in Northwest Ohio the northern strips of Fulton, Lucas and Williams were considered part of the Michigan Territory prior to 1837. It was after that time that they resolved the actual location of the boundary and the area became part of the state of Ohio. The Land transactions in this area seemed to bounce back and forth from Ohio to Michigan prior to the 1837 date. Finally there were entries after the 1837 law that transferred the land to it's proper jurisdiction. The whole time the family had never moved.
Boundaries have changed a great many times. Previously I have posted a link to he excellent map system at the Newberry Library on the internet that allows you to see the boundaries change on a map at a specific time. It will help you tremendously with understanding the changes in jurisdiction that have occurred in areas where are families have lived.