Much in Boing Boing lately about the Downsizing of Detroit into Semi-Rural farms. 

From the article by Cory Doctorow - 

"The city of Detroit is proposing to give over a quarter of its land to be turned into "semi-rural" fields and farms, with the surviving neighborhoods standing in "pockets in expanses of green." The proposal is politically charged (serving a death-sentence on a whole neighborhood is bound to be controversial) but the idea of "downsizing" Detroit seems to have wide acceptance."

Read the entire article and see links to more articles on this subject here.