Why are there so many snakes on Montana's roads?

A state program lets Montana nonprofits design special license plates to help raise funds for their organization. There’s an option for any charismatic Montana animal, university sports team or social cause you want to support. There are also three versions of a 'Don't Tread on Me' plate. One listener wants to know why. MTPR's John Hooks has the story behind the state's 200 license plate options – including the most popular choice.