Lactic.Acid is for the most part correct. Except for the lumberjacks.
Northern Minnesota is full of lumberjacks. Most of the small towns up here came into existence because of the logging industry, and lots of them are dying out or turning to manufacturing. There is still plenty of plaid flannel around, though.
On another topic,
Reasons that people live in (Northern) Minnesota:
snowmobiling(Polaris has a plant in Roseau)
lots and lots of water sports(blessed be the 10,000 Lakes!)
and last but not least, they can't get away.