Every year, the US throws out roughly 125 million tennis balls. That's enough to fill 21 Boeing 737s to the brim. And until recently, tennis balls were impossible to recycle. That's right, every ball ever produced would eventually end up in a landfill where it could take 400 years to decompose. But no more. The Hustle’s Matthew Brown visits West Virginia to track down what happens to tennis balls when they die. Check out The Hustle’s Side Hustles Database: https://offers.hubspot.com/side-hustle-ideas-database  Get the 5-minute newsletter keeping 2M+ innovators in the loop.