According to this article in the Guardian, marijuana is now the NUMBER ONE CASH CROP IN THE UNITED STATES. I'm sorry, didn't mean to yell.
As someone from the midwest, who's spent hours driving through apparently endless fields of corn and soybeans, I find the idea that American-grown weed is worth more than all that corn and soy just mind-boggling.
The study appears here on the Bulletin for Cannabis Reform page. You can read about their estimation methods here.
I remember reading, years ago, that marijuana had passed tobacco as the top crop in states like Kentucky and North Carolina. Well, here's the top ten producing states according to this table:
1) California (no surprise there)
3) Kentucky (do I swell with home state pride? Or what?)
6) North Carolina
9) West Virginia
Illinois placed 19, behind our Hoosier neighbors to the east (17). We are, however, way ahead of Iowa (43) and Wisconsin (27). Evidently cornfed meth freaks and brandy-swilling cheeseheads don't have what it takes to make good pot farmers.