Added instructions for installing USGS topographical maps into Google Earth! Thanks to the users at Google Earth Library for the work. If you are wanting to buy some of their more advance maps (seamless, no white borders) for Google Earth, they offer options at their site. Otherwise the free ones, which are in the instructions in our maps section, includes the white borders (non-seamless). Instructions were also added on how to view historical USGS topographical maps in Google Earth. Both are in PDF format. Head on over to the maps section and check them both out!