This KML network link displays a map overlay for USGS Contours (http://viewer.nationalmap.gov/) in Google Earth.
For some information on how it works, please see the main page and the FAQ.
To get started, simply download all 4 USGS The National Map map overlays on this site.(please log in first, see here why) and open it in Google Earth. Or checkout
Do you have comments, bug reports, or suggestions for other map sources? Please leave them below.