It depends on the year. Last year some parts of Minnesota had horrible tick populations. But it really depends on the season.
Last summer I heard reports coming from the BWCA that some people were finding hundereds of them after a few portages through the woods. There is a BWCA forum that I check out now and again that had one person report that his wife stopped counting them when she reached 700.
Normally all of northern MN has ticks and it should be routine to check yourself when coming out of the woods but normally its pretty manageable. You'll find maybe one or two at most if any at all, i wouldn't expect to find any more then that.
If you stay out of the deep woods and specifically tall grass you can probably avoid all of them. stay in the boat and you won't find a single one.
Sure, there are ticks all over Minnesota, but the ones to really look out for are Deer Ticks or as they are known, Blacklegged Tick. Deer ticks are normally found in central and southeast Minnesota but are now spreading North and West. Last year, in Minnesota, the highest risk of Lyme disease was in the east-central part of the state between the Twin Cities and Duluth.