The San Pedro: The Southwest's Last Free River
Near Benson, Arizona
The San Pedro River flows north from Mexico through a narrow corridor of cottonwood and willow threading across open desert between Benson and the border. It is one of the last major undammed, free-flowing rivers in the American Southwest, and it persists in a landscape where almost every other perennial stream has been pumped or dammed out of existence. In nineteen eighty-eight, Congress designated fifty-seven thousand acres along the river as the San Pedro Riparian National Conservation Area, the first riparian conservation area of its kind in the United States.
The area shelters more than three hundred fifty species of birds, roughly two-thirds of all bird species found anywhere in the country. A hundred of those species breed here; the rest funnel through during seasonal migrations between Central and South America and the north. The valley's ancient human story runs just as deep.
At Murray Springs, about thirty miles south of Benson, archaeologists excavating in the nineteen sixties found Clovis projectile points, stone tools, hearths, and the butchered bones of woolly mammoths, ancient horses, and camels left behind roughly eleven thousand years ago. The San Pedro Valley holds one of the densest concentrations of Clovis-era sites in North America. Hohokam farmers established agricultural villages along the river around the year five hundred, building ball courts and irrigation canals that sustained organized communities for eight centuries before population declined in the twelve hundreds.
The river that fed civilization here for eleven millennia still runs.
