Six hundred miles long from its source in the mountains of southwestern New Mexico to its confluence with the Colorado River above Yuma, the Gila River has been an important avenue for the movement of birds, animals, plants, and peoples across the desert for millennia. Many cultures have sprung up on its banks, and millions of people depend on the river today—whether they know it or not. Gregory McNamee, author of the prizewinning book “Gila: The Life and Death of an American River,” presents a biography of this vital resource, drawing on Native American stories, pioneer memoirs, the writings of modern naturalists such as Aldo Leopold and Edward Abbey, and many other sources. Think of it as 70 million years of history packed into an entertaining, informative hour. Presented with funding from the Friends of the Prescott Public Library.