Where in the World are Grandpa and Grandma - delayed edition

Well - this will be a little catch up on our game.  The next state that we will describe is a very large state that has the largest freshwater lake in the world on one of its borders.  The name of the state was taken from a native american word meaning, "sky tinted water."  One of its other borders has the largest river in the United States washing by.  This state has 10,000 inland lakes.  Its capital is named after my brother and Bing's brother..........There are some very large cities but the tall grass prairie where the Prairie Indians hunted bison covers acres and acres beyond the cities.............This state entered the union on May 11, 1858.............A few square miles in the north of this state produce 75% of the nation's iron ore and one of its cities is the largest inland harbor for  the international shipping trade.  A fun nonsense fact:  The mascot for its nickname is an underground rodent..............Can you name this state?????