The World Championship Punkin Chunkin Contest & Festival is held each year in Sussex County, Delaware and involves 17 categories of catapults, a beauty contest, road races, carnival and lots of music. The first one was in 1986.
Other states hold their own Pumpkin Chuckin' contests. Ludlow, Vermont holds a Zukapult contest to fling zuccinni. As far as we know, this would be the first (and long overdue) Vermont Pumpkin Chuckin' Contest.
see Wikipedia: Pumpkin Chunking