CCC

Rivet Head posted this photo of a group at a Civilian Conservation Corps (CCC) camp.  I knew that the CCC was, like the Works Progress Administration (WPA) and National Recovery Administration (NRA), part of FDR's New Deal.  Only recently I learned of the work it actually accomplished, other than providing food, shelter and employment for unmarried men.  Basically, the CCC is responsible for the "look" of the U.S. National Parks.  From Wikipedia:

During the time of the CCC, enrollees planted nearly 3 billion trees to help reforest America, constructed trails, lodges and related facilities in more than 800 parks nationwide and upgraded most state parks, updated forest fire fighting methods, and built a network of service buildings and public roadways in remote areas.