Cattle brought most of the gringos to South Texas, but oil gave them a glimpse of wealth and power. Despite their light skin, the Parr men, patrOns of South Texas, spoke Spanish as their first language. Like the cactus and barbed wire, the bougainvillea and orange tree in this arid land, they flaunted their charm and made no excuses for the thorns. They paid medical bills for the Hispanics. They helped their children go to college. But when it came time to vote, their benevolence demanded obedience.

In Duval County, it's politics as usual. This is the world,...