If you will turn to the map again, you will see still other places where a short canal may open up an entirely new and important water route. From Chicago to Lockport, Illinois, is only thirty-seven miles, but Chicago is on Lake Michigan, while Lockport is on the Illinois River, a branch of the Mississippi. This canal, a large part of which is now in operation, is a part of the Lakes to Gulf waterway. One plan is to broaden and deepen the channel so that large vessels may pass, without unloading, from the Lakes to the Gulf of Mexico. Another proposed canal which would be undertaken largely by individual states and a part of which is already completed, would afford a safe inside passage connecting the many bays, channels and navigable rivers of the Atlantic coast. Still another proposed measure is the cutting of a canal from the southern end of Lake Michigan to the western end of Lake Erie at Toledo, Ohio, to avoid the long haul up Lake Michigan and down Lake Huron again. The United States now has 25,000 miles of navigable rivers and a nearly equal mileage of rivers not now navigable but which might be made commercially important; five great lakes that have a combined length of 1,410 miles, 2,120 miles of operated canals, and 2,500 miles of sounds, bays and bayous, that might be joined by tidewater canals easily constructed, less than 1,000 miles long altogether, and making a continuous passage from New England to the Gulf of Mexico. In all, our waterways at the present time are 55,000 to 60,000 miles long, the greatest system in the world, but almost unused. The most important waterway improvement so far completed, is the Sault Ste. Marie, or the "Soo" canal which cost $96,000,000. A depth of eight feet was increased to twenty-one feet. The traffic has risen in sixteen years from a million and a quarter tons to forty-one and a quarter million tons. A large proportion of the United States is not naturally fitted to be the home of man; at least, it is not fitted to produce his food, and except on the lofty mountains the reason for this will almost always be found to be either a lack or an excess of water. In some parts of the country, there is, as we have seen, little rainfall. These arid or semi-arid lands must be provided with water for drinking purposes and for agriculture. The diverting of water courses into canals and ditches so that water can be carried to these waste lands is called irrigation. In other parts of the country where rains are abundant, serious floods occur every year, often many times in a year. Thousands of acres of land thus subject to overflow are lost to use. The holding back of these flood waters in the upper part of the rivers, and so preventing these overflows, is termed storage of waters.