Interesting. I didn't realize that about MN state parks. I did ACA's Northern Tier route. We spent 2 weeks in MN because we did the longer of the two options and had a couple of rest days, including one in Minneapolis. We stayed at Lake Itasca S.P. (in the HI Hostel) and Hennepin S.P. in Isle, but I never realized that alcohol was not permitted. I am surprised since it seemed to be easy to get beer just about everywhere. We even stayed at a private campground that had it's own bar with beer on tap.

Alcohol is not permitted in PA or NJ state parks, which are what I frequent most. If you don't openly violate the rule and don't get drunk and cause problems, I don't think the rangers really mind. If you visit the recycling/trash disposal area of one state facility in NJ that I visit a couple of times of year you will find plenty of empty alcohol containers in the receptacles. A few years ago I stayed at one private campground in PA that allowed you to drink, but you couldn't display alcohol containers, and the list of rules expressly required beer cans/bottles to be in cozies. Also, you could not leave your campsite with alcoholic beverages. I then realized that the owners had a religious bent, so it made sense.