In July 25, 1965, near 10,000 spectators traveled to the Cleveland Metroparks Polo Field to witness the first-ever North American horse show jumping grand prix — the Cleveland Grand Prix. The event gave birth to the multi- million-dollar sport of grand prix horse show jumping in the United States. Held on the final day of the Chagrin Valley PHA Horse Show, the Cleveland Grand Prix was defined by the 844-yard course of 16 obstacles designed by Laddie Andahazy and D. Jerry Baker. Twenty riders from six countries—the United. States. Canada, Mexico, France, Great Britain, and Germany · competed over the course. Mary Mairs Chapot won the event on her horse Tomboy and her husband Frank, an Olympic veteran, finished second aboard Manon.