Ever wonder why Africa is so poor? Here's one reason: In many parts of the continent, it's hard to ship goods anywhere without paying serious bribes and incurring infuriating delays. Via Felix Salmon comes this very interesting study (pdf) of West African roadblocks (read: places where armed men demand money).

The three-page report, which was funded primarily by USAID and the World Bank, contains this handy map of roadblocks along three major routes:

Trucking your wares from Bamako, the capital of Mali, to a port in Ghana is a journey of a little over 2,000 kilometers. On average, the report says, it will cost you about $200 in bribes, and the nearly 50 forced stops along the way will delay your journey by almost 4 hours. As Salmon observes, "This kind of study is crucial to understanding real trade barriers, as opposed to just the ones which get fought over at international fora such as the WTO."

Coming soon, I hope: a Google Maps mashup for the entire continent.