Big tree "Wanona," showing the relative size of other conifers compared
with big trees. Mariposa Grove.
In 1906, after long effort, the famous Mariposa Grove of large trees in
California was made a national reservation. During the same year a bill
was passed by Congress providing for the preservation of Niagara Falls.
Public opinion had been aroused by the campaign of the American Civic
Association. Power companies had multiplied so rapidly that it seemed
the whole volume of water was about to be used for commercial purposes
and that the most famous object of natural scenery in the United States
would be destroyed.