NATURAL WATERWAY& IN THE UNITED STATES HARTS. 547 



this important branch of the Nation's activities, only the more con- 

 spicuous instances can be referred to in a paper of this kind and 

 only a brief general analysis given. 



The work of deepening and regulating river channels in the 

 United States has been much more extensive than is generally sup- 

 posed. The amount spent on rivers, up to 1913, exclusive of harbors 

 and canals, has amounted to $402,792,000, and there is at present 

 river work under construction amounting to $187,064,000. New work 

 recommended by the engineers but not yet adopted by Congress 

 amounts to $130,315,000. 



The interior natural waterways of the United States may be divided 

 into four general divisions, corresponding to the main geographical 

 divisions of the country. Foremost of these is the lake system along 

 our northern border. The other divisions are the portions separated 

 by the two main mountain ranges — the Appalachians on the east 

 and the Rocky Mountains on the west. These divide the United 

 States into three main portions, the Atlantic Slope, the Pacific Slope, 

 and the Great Mississippi River Basin, 



With the exception of the Hudson and the Delaware, there are but 

 few large rivers on the Atlantic slope, and these are largely tidal. 

 On the Pacific slope, the Sacramento and the San Joaquin Rivers 

 form a system of navigation reaching both north and south in the 

 State of California; and the Columbia River, farther north, offers 

 a transportation line into the wonderfully rich and fertile Northwest. 



It is in the central portion of the country, however, that the great- 

 est opportunities for channel construction exist, for the great Mis- 

 sissippi Valley is traversed by one of the longest streams in the 

 world, which, with its tributaries, offers many thousands of miles 

 of navigable waterways. 



The distribution of streams in this country and their total navi- 

 gable lengths are shown in the following table : 



streams. 



Streems. 



Navi- 

 gable, 

 length. 



Tributary to the Atlantic Ocean 



Tributary to the Gulf of Mexico^ exclusive of the Mississippi River and tributaries. . 



Mississippi River and tributaries 



Flowing into Canada | 2 



Tributary to the Pacific Ocean 38 



Miles. 

 5,365 

 5,212 

 13,912 

 315 

 1,606 



Total 295 



26,410 



(P. 28, "Transportation by Water," Report of Com. of Corporations, 1909, Part I.) 



These navigable lengths must be considered as approximate, as 

 definite lengths of navigable streams are seldom exactly determinable. 

 Nearly all these streams are of comparatively shallow depths, and 

 are, in the main, available for light-draft boats only. "Forty 



