John G. Armbruster of Lamont-Doherty Earth Observatory of Columbia University has graciously shared his research on historical earthquakes in Ohio and adjacent areas and has greatly improved the accuracy and completeness of this catalog. He has added new earthquakes to the list, relocated a number of events, and removed some events generated from nonseismic sources (explosions, sonic booms from meteorites or aircraft, meteorological phenomena, etc.) listed in previous compilations.