Maps can provide fun and interesting way to research your ancesstors. Historical Plat Maps frequently show ownership of land. The following links include a variety of sources for your research.
David Rumsey Map Collection
Historic Map Works
Use search box type “county, state Plat Map” for example.
University of Iowa Libraries
Use their search box “county name Plat Map” for example.
Sanborn Map Abbreviations
Atlas of Historical County Boundaries
RESEARCH BY CATEGORY
RESEARCH BY STATE
RESEARCH BY COUNTRY