28 THE BOOK OF FORESTRY 
The value of our waterways in affording cheap trans- 
portation to heavy freights has been overlooked f 
some time on account of the greater popularity of the 
railroads. Under present indications it appears that 
canals and inland waterways of all kinds are coming 
into their own. New York has spent over one hundred 
million dollars on her barge canal and the people re- 
cently voted in favor of an additional twenty-seven mil- 
lion dollars to complete the work. There are altogether in 
the United States 295 rivers, considered navigable and 
the total length of their navigable waters amounts to 
26,000 miles. Numerous State and local associations 
are interested in their development and the use of these 
inland waterways will doubtless be greatly increased 
when terminals, etc., are constructed. The maximum 
development of streams for navigation as well as for 
power purposes depends directly upon even flow of the 
run-off, which can best be maintained at the source by 
keeping the watersheds perpetually under cover. 
Minerals—At the risk of being tiresome it can be 
said regarding minerals as well as of lands and forests 
that the United States has greater mineral wealth than 
any country on the globe. While in the production of 
gold our output is exceeded by South Africa, we excel in 
variety, for there are only two or three metals of any 
importance which are not found within our boundaries. 
The most important metal which we lack is nickel. We 
produce two-thirds the world’s output of petroleum; 
sixty per cent of its copper; forty per cent of its coal 
and iron; thirty per cent of its zinc. 
The former waste of some of these minerals has been 
previously mentioned and their supply is by no means 
endless. The supplies of high grade iron ore now in 
sight will probably be exhausted by the year 1930, when 
