In the 1930s, lumbermen began logging bald cypress trees in south Florida because their knot-free trunks and rot-resistant wood were highly valuable, and lumber companies built railroads on levees to haul huge logs out of the swamp, accelerating the harvest of cypress. In 1952, logging began at the southern end of Corkscrew Swamp, the largest remaining stand of unlogged old-growth cypress forest, prompting concerned citizens and a coalition of organizations including the National Audubon Society to work to save it. With the cooperation of the lumber companies that owned the land and support from donors nationwide, Corkscrew Swamp Sanctuary was established in 1954 with 2,880 acres of prime cypress swamp. Since then, continued cooperation and support have allowed the sanctuary to add another 10,680 acres, build and rebuild the boardwalk, and protect the water supply that sustains Corkscrew Swamp and the surrounding region.