American Whitewater works to preserve the natural state of U.S. rivers.

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The world's rivers draw people to them like a hearth, the center of life for civilizations since the beginning of time. Rivers carved out the Grand Canyon, and they built Niagara Falls. They house thousands of species of fish and provide transportation, drinking water, irrigation and electricity to billions of people. Rivers offer swimming, canoeing, rafting and kayaking, and provide a living to fishermen and recreation guides all over the world.

They seem like a constant presence -- always flowing, rising and falling over time. In the United States alone, they run for 3.5 million miles (5.6 million kilometers) and touch every corner of the country [source: NWSR]. But rivers are not indestructible. They are just as susceptible to the downsides of human intervention as any other natural formation, perhaps even more so. The rate of extinction for freshwater species is five times greater than for those living on land, and U.S. riverbank habitat is 70 percent wiped out [source: NWSR]. Rivers are falling prey to such culprits as damming, pollution and development at an alarming pace.

In the face of this high rate of destruction, dozens of organizations looking to protect the world's rivers have popped up around the globe in the last 50 years. One of the most active is U.S.-based American Whitewater, which works to preserve the natural state of America's rivers so our children's children's children can enjoy them, too.

But it's not all about preservation. The organization has its fingers in all sorts of river issues. In this article, we'll find out what American Whitewater does, how it aims to make a difference and why you might want to get in on the action yourself.

To begin with, what's the point of American Whitewater? Is it all about those frothy, fast-moving currents that carry screaming rafters in vacation photos?