Geography isn't just about drawing maps. A map is usually a base we build to show some data.
Let's turn this into a map of the world's airports. Actually, scratch that - let's do something cooler. Let's make a map of CIA rendition flights out of the US. To do this, we'll still need the world's airports, as the airport values in the Rendition Project's dataset use the airport short codes, not latitude and longitude.
The first step is fetching the airports.dat dataset from http://openflights.org/data.html and the Rendition Project's U.S. flights data from http://www.therenditionproject.org.uk/pdf/XLS%201%20-%20Flight%20data.%20US%20FOI%20resp.xls. You can also find it in the examples on GitHub at https://github.com/aendrew/learning-d3/blob/master/chapter4/data/airports.dat ...
