Photographer Tim Palmer presents hundreds of images of the U.S.'s rivers and discusses their protection and the life within them.

"America has more than 250,000 rivers, coursing over more than 3 million miles, connecting the disparate regions of the United States. On a map they can look like the veins, arteries, and capillaries of a continent-wide circulatory system, and in a way they are. Over the course of this nation's history rivers have served as integral trade routes, borders, passageways, sewers, and sinks. Over the years, based on our shifting needs and values, we have...