599th Co. C.C.C. Camp 505-13 Cadiz, Kentucky
photo by S. Spencer Stuychkoff
The Civilian Conservation Corps started in the early years of the Roosevelt administration and lasted until World War II. It put young men to work planting or seeding forest areas, thinning out overcrowded growth, and carrying on other useful conservation activities. They also built bird refuges, sanctuaries, dams, and storage reservoirs to hold water.
More on CCC.
Some interesting stuff on CCC: A History of the Civilian Conservation Corps at Mammoth Cave National Park by Kelly A. Lally, December 1987