No less than 1,600 steamboats run upon the Mississippi river and its tributaries. The total value of these is estimated at $60,000,000.--The Mississippi drains an area of 1,200,000 square miles, washes the shores of twelve States, and from the Gulf of Florida to the source of the Missouri it is 4,500 miles in length, its average depth 50 feet, and its width over half a mile.