The government's "war on drugs" has been both a tremendous triumph and an abysmal failure. Drug warriors have been very successful. We have all seen media images of police stings involving massive amounts of money, drugs, and firearms. However, this has had no impact in local markets. Illegal drugs are available just about everywhere and at prices that have fallen in real terms over time. The amount of pot that could be bought for $10 at a local high school in 1980, for example, is likely the same quantity that could be obtained for $10 today.
Underground Economy @ Wikipedia
Off the Books: The Underground Economy of the Urban Poor by Sudhir Alladi Venkatesh
In Search of Respect: Selling Crack in El Barrio (Structural Analysis in the Social Sciences) by Philippe Bourgois