Headlights, Imperial Sand Dunes, California, 2005Photograph by Gerd LudwigHeadlights stream up and down the fluid banks of Imperial Sand Dunes, southeast of California's Salton Sea, in this time exposure. An off-roaders' paradise, the dunes were blown from the dry bed of Lake Cahuilla, the sea's ancient ancestor. More than a million fans hit the dunes each year, pumping $54 million into local coffers. The cost? Brawls, fatal crashes, and run-ins with endangered species.