If your shore fishing in the Minneapolis area....try Minnetonka.There are plenty of areas where you can catch a limit of crappies.Try picking up the Twin Cities Fishing Guide to start.Otherwise try fishing Grays Bay on Hiway 101 or Tanager Bay near the railroad trussel.There is a bycycle path you can walk down to get to Tanager.
If your dead set on fishing the Mississippi...try down near Red Wing.There are ample opportunities down there.Or you can try the St.Cloud area by St.Cloud University.