"It's not widely publicized by the U.S. Agriculture Department, but marijuana is America's largest cash crop--topping the value of corn and wheat combined. A 2005 analysis by Harvard economist Jeffrey Miron found that legalization would generate $7.7 billion a year in enforcement savings for local, state, and federal taxpayers, while producing annual tax revenues of $6.2 billion." -- Jim Hightower, 2009-11-23 [thanks to Penguirl for linking to it.]
(That the next available spot in the quotes-queue when I added this was also the anniversary of the repeal of the 18th Amendment (Prohibition), was a lucky accident.)