We have in the past looked at a lot of content provided by the USGS. The USGS is the provider of the data for the ‘earthquakes layer’ in Google Earth. We also looked at some of their future plans, like the 3D Elevation Program (3DEP).
We recently came across this article about USGS’s topoView. Despite its name, it is not for actually viewing maps but rather, it helps you find and download them. The maps in question are historical topographic maps of the US from the USGS’s vast collection.
The maps can be downloaded in various formats, including KMZ for viewing in Google Earth.
A topographic map of Fort Smith, Arkansas, from 1887.
We found it interesting in the Fort Smith map above just how much the river has changed since then. When you have downloaded a KMZ and loaded it in Google Earth, expand it in ‘Places’, find the ‘Map’ item, right click and select ‘properties’. In the Image overlay dialog box that appears you can adjust the transparency of the map to compare it with the modern imagery in Google Earth.