You have to be at the gate at least 20 minutes before departure time. Figure at least half an hour to wait in line to check in, another half an hour to make it through security, and 15 minutes to walk to your gate (the gates in Minneapolis aren't near security at all). So if you wanna cut it really close, show up an hour before departure time. To be safe figure about 2.5 hours. 4 hours is a bit excessive.

If at all possible, pack light and don't check your bags. You'll wait forever to pick it up at the baggage claim, and that's the worst kind of waiting because you already done got off the plane.