For that missing (or not missing) ancestor, do you know where the nearest three of these buildings, geographic features, organizations, social groups, etc. were when your ancestor lived in the area. It could help you through those research road blocks. Things to think about include the nearest three:
- county seats,
- county lines,
- federal land offices (if applicable),
- train stops,
- towns where people could trade and get supplies,
- employers who employed more than a few people,
There are others besides these. In some cases. three may not be enough. In some cases it may be more than you need for effective research.