Did you know that you can overlay every available USGS topo map on Google Earth for free? And that you can set it up in a matter of minutes? Here’s how:
1) Install Google Earth if you haven’t already.
3) When prompted, save the file to your computer.
4) Find and double-click the file. It will open automatically in Google Earth.
5) At this point, you’re essentially done and can begin zooming in and out on topo maps for the entire country. You need to take one more step, however, to ensure that this file remains available for future use. When you first open the file, you will see a “NGS_Topo_US_2D” icon under the “Temporary Places” folder in the left-hand “Places” column. To make this a permanent addition, move the icon to the “My Places” folder; just drag it over and drop it into “My Places.”
One great feature of this layer is that you can change its opacity. That is, you can fade it in and out so that you either see just the topo map, just the satellite image, or both simultaneously. To do so, simply slide the bar in the opacity adjustment (circled in red in the bottom picture below).