The 7,000 streams that become the Mississippi River

A new online tool, called Streamer, released by the Department of the Interior allows users to select any major stream and trace it up to its sources or down to its watershed. As a new way to visualize and understand water flow across America, Streamer can be used to see where the streams around you are getting their water (and pollution).

For example, Slate used the tool to export a map showing all the major tributaries that feed into the Mississippi River, illustrating the rivers huge catchment area of approximately 1.15 million square miles, or 37 percent of the land area of the continental U.S.

In addition to making maps, Streamer creates reports about your stream traces and the places they pass through.