These are but a few examples taken from our own history of the importance of rivers. They could be duplicated in almost every country of the globe.
164.Great Rivers of the United States. -There are four great river basins wholly or partly within the United States： the St. Law- rence， the Mississippi， the Columbia and the Colorado. The first two of these are navigable for great distances and furnish unexcelled interior waterways. Notwithstanding the great development of railways they still exert a vast influence upon the commerce of the country.
DRAINAGE BASINS OF THE UNITED STATES.
Notice the positions of the divides separating the different drainage areas.
The St. Lawrence River with the Great Lakes， which are geographically a part of it， is the greatest internal waterway in the world. From the head of Lake Superior to the mouth of the St. Lawrence， a distance of about 2400 miles， by aid of the canals which have been built around the rapids and falls， vessels of 14 feet draft can pass to the sea. More tonnage passes through the "Soo" canal between Lake Superior and Lake Huron than passes through the Suez canal. Here pass the greatest fleets bearing wheat， iron， and lumber that the world has ever seen.
The old river which once drained this region passed through various vicissitudes before the present noble waterway was formed. From Montreal to the sea it has been drowned by a depression of the land. ItsTHE "Soo" CANAL AT SAULT STE. MARIE.
Notice the "whale-backs，" a type of boat peculiar to the Great Lakes.
upper basin has been enlarged in places by the action of the glacial ice， and in other places it has been dammed， thus causing lakes and falls.
The Mississippi and its tributaries offer navigable waterways ofabout 9000 miles. It is the greatest navigable river system in the world. From the Rocky Mountains on the west to the Appalachians； onTIE JETTIES OF THE MISSISSIPPI.
To keep the river from silting up its channel， it is confined between jetties and made to flow swiftly.
the east and from the northern border of the country to the Gulf， the spreading arms of its tributaries stretch out ready to bear to the ocean by cheap and easy paths the products of this vast interior basin. By theDELTA LAND OF THE LOWER MISSISSIPPI.
aid of the Panama canal these varied products may travel directly by water without more than one or two re-shipments from their source in the vast continental interior to the uttermost parts of the earth.
This noble river presents in its eventful history an epitome of the geographical history of our continent. It winds its masterful way over the oldest and youngest rocks. For part of its course it follows a valley built long before the Glacial Period shrouded the northern part of the continent in ice. In the northern part of its course the blanket of débris left by this vanished ice choked its path and forced it to seek a newTHE COLUMBIA RIVER AND ITS OLD FLOOD PLAIN.
channel. For the southern part of its course its mighty sediment-laden waters built new lands that it might extend its dominion.
At times in its history its might has been greater than now and at times less. But through all its history it has borne to the ocean the ceaseless current flowing from the heart of our continent. To it the modern geographer turns again and again as an inexhaustible record of geographical development. The geographical， political， industrial and commercial history of this continent are closely connected with this， its mightiest artery.
The Columbia River， although navigable for a distance of only 500 or600 miles， and thus never destined to have the commercial importance of the St. Lawrence and the Mississippi， presents features of great interest. Guided by this stream the first settlers found their way to our northwest territory. Along its depressed mouth the rich and prosperous states of Washington and Oregon were nurtured through their infancy. Over its possession Englishman and American long contended.
This contention of man， however， was but an echo of the long contention of the river itself to hold its course. Flowing in a region of growing mountains， it was forced again and again to cut its way through barriers uplifted across its path. Sometimes for a time it was checked and forced to raise itself into a lake in order to surmount the obstruction placed in its way， but its strength never failed， and so through new-born ridges， through lake beds born of its own struggle， through growing depressions filled by its own labor， it held its course steadfastly to the sea. For part of its way it flows through ca？onlike valleys， and its main tributary， the Snake， has built for itself through great beds of horizontal igneous rocks a ca？on but little inferior to that of the Colorado.
The fourth great river， the Colorado， has industrially and commerciallyattained but little usefulness. Although navigable to about 400 miles from its mouth there is little need in the country it traverses for transportation in the direction of its course. But what it lacks in utility， it makes up in scenery. To no other river on the face of the earth has the opportunity been given to show its sculpturing power as to the Colorado.
Flowing as it does through an arid region of nearly horizontal rocks， it has carved a giant trough for itself， leaving upon the lofty sides the uneffaced chisel marks of all its erosive helpers. The rill， the rivulet， the intermittent torrent， the sand blast of the scouring wind， the pull of gravity， the varied resistances of the rock layers， the structure and composition of these layers have each and all left their peculiar impress upon the resulting sculpture. Standing beside this mighty chasm， one is impressed， as nowhere else， with the mighty power of erosive agents.
THE COLORADO RIVER.
Flowing through a deep-cut， narrow valley.