There's a lot you can do with a good map. Figure out how to get to Valhalla, New York from Pittsburgh, PA. Find the nearest ATM machine to your house. Even figuring out the best bus route across town. Unfortunately, the available mapping systems and their data such as Mapquest, Terraserver, and Street Atlas, are largely proprietary requiring licensing fees and often-limited access to the raw map data. As such, open source development of good geographic software has been limited.

Fortunately, the U.S. Census has been conducting a systematic survey of the entire United States in a project called TIGER/Line. This treasure trove of data contains not only street information, but also waterways, power lines, political boundaries, public buildings, parks...most everything you can draw on a map. Add to this data from the U.S. Geological Survey along with declassified government satellite photos and you have the potential for an extremely accurate, extremely detailed map. And it’s all public domain data! Perfect for open source!

We will lay open this vast wealth of data and dig through its often baroque and confusing formats to show how the data can easily be sifted through and parsed with the Geo::TigerLine module. We'll also walkthrough the Geo::Walkabout mapping library, its interface, algorithms, strengths, and shortcomings. Finally, some applications in development will be showcased.