Photojournalists capture history as it's made—and few have done so as successfully as Dirck Halstead, Diana Walker, Wally McNamee and David Hume Kennerly. Collectively they've circled the globe, produced close to 200 magazine covers, earned numerous awards and photographed every president from Dwight Eisenhower to George W. Bush. Through it all, their unforgettable images have shaped the way we view our world.