National Geographic : 1920 Jul
Photograph from E.W. Nelson THE HUGE CANDELABRA CACTUS OF MEXICO OFTEN REACHES A HEIGHT OFSIXTY FEET The average rainfall along the Mexican border from the Rio Grande to the Pacific is probably less than inany other section oftheUnited States-about eight inches annually, and on the Yuma and Colorado deserts it drops to two or threeinches. This boundary line, more than 700 miles in length, crosses only five permanent running streams. It is remarkable that, although arbitrarilychosen, theline from theRio Grande to the Colorado River follows almost exactly the summit of the divide which separates the waters flowing north into theUnited States and those flowing south into Mexico.