A watershed is an area of land that soaks up rain as it falls to the ground and delivers it to a larger body of water. Every part of land around the world is part of a watershed. For example: when rain falls on a mountain, small streams form from the rainfall and these streams rush down the mountain because of gravity. The streams meet with larger bodies of water, like rivers, and may empty into a lake or into the Ocean.

The Eastern part of North America relies on several important watersheds; the Mississippi River is one of them. The Mississippi River is formed by all of the rain that falls into smaller rivers and streams around the Mississippi, and eventually the streams connect to the Mississippi River which flows down to the Gulf of Mexico. Because the Mississippi River is so long, the land around it that is part of the Mississippi River Watershed is huge. In fact, Thirty-one out of the 48 states on the continental U.S are included in the Mississippi River Watershed. Rain water can also carry pollution and litter into the rivers that empty in our oceans. It all becomes a part of the water humans and other living creatures need to survive.