This is just what I was looking for. It also shows the U.S. border.

After it is installed to MapSource use the "Map Tool" button and select/highlight all of the map. Then click on the "Map Set Name" button in MapSource and name it "U.S. Borders, States & Counties". Since this is a transparent map, it is very useful to name it from gmapsupp.img to gmapoem.img because there is no need to turn it off and it is very small in size (less than 2 MB). Rep added. Thank you so much!!!