With the recent addition of over 100 new historical maps, there are now 120 maps in the Rumsey Historical Map layer in Gallery layer in Google Earth, and these maps can now be seen in a new layer in Google Maps. The original 16 historical maps, launched in November of 2006, have been augmented by adding many more maps of cities, regions, countries, continents, and even globes.

The method of finding the maps and enabling them has improved as well – all the maps are now represented by icons on the earth which open balloons that allow you to display the historical map on Google Earth and get more information.

Here's an example of what you'll see in Google Earth:

And here's a peek at the new layer for Google Maps:

Highlights of the new maps include a 1792 Celestial Globe (also in Google Sky), the first accurate survey of Yosemite Valley, California, from 1883, new maps of Los Angeles, San Francisco, Seattle, New York, Washington DC, Denver, Chicago, Moscow, St. Petersburg, Calcutta, Lima, Paris, Madrid, Rome, Beijing, Tokyo, Kyoto, and more – all from times ranging from the 18th to the 20th centuries. Also included are new country, regional and continental maps from Europe, South America, Australia, Asia, and North America.

I appreciate the work done by Wei Luo and Matt Manolides of Google Earth and the KML design by David Lewis in the UK in bringing these new maps online, as well as the innovative work by Peio Elissalde and Nicolas Cherel of Geogarage in Nantes, France, in creating the map layers in Google Maps, using the Google Maps API.