We’re knee-deep in primary season. Super Tuesday is right around the corner, where voters in a dozen states take to the polls. It feels like primaries have been around for as long as there have been elections. But did you know they were actually invented by Teddy Roosevelt? Geoffrey Cowan tells the story of how and why Teddy Roosevelt made our electoral system even more democratic in his new book 'Let the People Rule: Theodore Roosevelt and the Birth of the Presidential Primary'.