Googlified

Googler (Noogler, actually) Matthew Gray shares some interesting statistics about the locations mentioned in the Google Book Search index - over a million books - with a map.

Using a set of data that was previously collected by David Petrou, another Googler, for the purpose of visualizing “places mentioned in books on a map”, Matthew “wrote a little program using [some] cool Google stuff” and “had a map in forty-five minutes” with the Google infrastructure, instead of days on a desktop. Wow.

As you can see in the above image, most of the places that were mentioned are in the U.S., Europe, and India. “Filtering the map by publication date, you can see global patterns like the growth and westward expansion of the United States in the 19th century.” Matthew explained, and you can find the maps here.

I am wondering what are the colors represent: does it go from green, blue, to red?