San Dimas, California, USA - The IGSA Unted States National Championships begin today at Frank G. Bonelli Park in San Dimas, California. Zak Maytum from Boulder, Colorado is the defending Downhill Skateboarding Champion. He won last years race over 2007 Winner Jimmy Flindt in a last second pass down the final straightaway. Both riders will be back to battle it out once again in addition to many of the other top downhill skateboarders in America.