The Four Sixes is not a relic, showpiece, or preserve. It's a working cattle ranch, some 290,000 acres of West Texas prairie carefully used. Here, men still earn their livelihoods on horseback, not out of blind adherence to tradition, but out of necessity. Since Samuel "Burk" Burnett began buying rangeland in King County in the 1890s, his cowhands have relied on methods developed by early vaqueros and refined on the great trail drives. In managing...