From The Santa Fe New Mexican:
July 3, 1914: Las Vegas — The main stunt in the Las Vegas celebration of Independence Day will be the elaborate program arranged by Dr. W.T. Brown … . There will be a greased pig race, running races, burro races, pony races and basketball on horseback, which it is said has polo looking like a parlor amusement. The riders are required to gallop 100 yards, pick a ball out of a box on a pole 3 feet high, then gallop back and throw ball into a box on a post eight feet high; $10 will be the prize for the rider that puts the ball in the 3 foot box.