NATTJUAL waterways in T-HE united states — HARTS. 659 



ticiilarly in the lowest six pools; and many of the steel mills of the 

 Pittsburgh district are also on its banlcs in the lower part. Most of 

 the traffic of this river is coal carried to the mills of Pittsburgh, 

 or carried to the harbor of Pittsburgh in small tows of three or four 

 barges, there to be made up into larger tows for shipment, at high- 

 water stages, down the Ohio to other river points below. This river 

 is canalized, by fixed dams, throughout its entire length of 131 miles. 

 Traffic on this stream has increased enormously in recent years. 

 The conmaerce from 1890 to 1912 was as follows: 



Tons. 



1890 4, 652, 104 



1895 4, 183, 596 



1900 5, 233, 110 



Tons. 



1905 9, 211, 752 



1910 11, 486, 278 



1912 11, .575, 239 



This system of lock and dams on the Monongahela was acquired 

 by purchase by the United States in 1897, at a cost of $3,761,651.46, 

 and since that time three locks have been rebuilt and their dams 

 equipped with movable tops, at a cost of about two and a quarter 

 million dollars. In 1913, Congress ordered the rebuilding of Lock 

 No. 6, at an estimated cost of $356,200. This river has had a very 

 marked effect on the enormous steel industry of its region, by re- 

 ducing the cost of coal. Its location is very favorable, and it has had a 

 very important share in the development of the great steel mills of 

 the Pittsburgh district. 



It should be mentioned, however, that the statistics of 1914 show 

 that the commerce on the 55 miles of river above Lock No. 6 is in- 

 significant as compared with the rest of the river. Although coal is 

 mined along this part of the stream, comparatively little is shipped 

 by water. The economic value of Locks Nos. 7 to 15 inclusive is thus 

 seen to be slight. The reason for this is not apparent. 



The Allegheny Eiver, which joins with the Monongahela to form the 

 Ohio, is mostly used in the lower 25 miles, where up-stream navi- 

 gation is the main movement of traffic consisting mostly of Monon- 

 gahela River coal for the steel mills along the lower 6 miles of the 

 stream. Practically no coal comes down the Allegheny, for the 

 reason that the coal fields, which are said to be as extensive as in 

 the Monongahela Valley, are of thin veins and so can not yet compete 

 with the Monongahela mines. In this lower 25 miles the locks and 

 dams were completed. No. 1 in 1903, No. 2 in 1906, and No. 3 in 1904, 

 all at a cost of $1,690,000. In 1912, a new project was adopted by 

 Congress providing for extending slack-water navigation about 36 

 miles farther up-stream by constructing five new locks and dams, at an 

 estimated cost of $2,788,000. No work has been done on this new 

 project because of a provision of law which requires that before work 

 can be begun satisfactory assurance must be given that the channel 

 spans of bridges which obstruct the river at Pittsburgh will be modi- 



