You can do better than geocoding: use one of the county-level shapefiles from the TopoJSON project: https://github.com/topojson/us-atlas https://github.com/topo

You can do better than geocoding: use one of the county-level shapefiles from the TopoJSON project: https://github.com/topojson/us-atlas https://github.com/topojson/us-atlas At the very least, if you do just need point-level info, you can get the centroids of the county shapes.