It's an hour before showtime and Rob Gann is running late. He has to get his makeup on, climb into his costume, and build a flash-bang firework that will provide the big noisy finish for his act.

DENVER — From the time he was in fifth grade, Richie Harris aspired to be a rodeo clown. “Ever since that day, I said, ‘This is what I want to be,’” he said. Coloradoan Richie Harris (pink shirt) has ...