[Source Photo: Strekoza2/iStock] advertisement advertisement If fertilizer runs off a farm in southwestern Montana, it could end up traveling more than 3,400 miles through streams and rivers in North Dakota, South Dakota, Iowa, and Missouri, and then down the Mississippi River to the Gulf of Mexico, where it might end up contributing to a giant algae-filled dead zone. Plastic trash that lands in a stream in West Virginia might make a similarly long journey—around 3,000 miles—to the same place. advertisement [Screen Capture: Samlearner.com]A new map called River Runner lets you trace the long path of water throughout the U.S.: Click on any spot or enter an address, and it will show where the water is likely to flow. Data analyst Sam Learner started working on the project after thinking about how water travels from the Continental Divide. “I though that journey would be really interesting,” he says. “If we start at the top of a mountain on the Continental Divide, just watching this split—one journey a few hundred miles to the Pacific, and another to the Gulf of Mexico. As I started digging into the data, I realized that the scope of it could be much bigger.”