William duPont was the last private owner of Montpelier.William and his wife Annie, made substantial changes to the house, enlarging it, renovating the formal garden, and adding many outbuildings and stables. Their daughter, Marion duPont Scott, was an accomplished horsewoman who transformed Montpelier into a first class Thoroughbred breeding and racing facility, building a state of the art steeplechase course and a flat training track.  As an owner, Mrs. Scott bred a series of winners from excellent Thoroughbred bloodlines. In 1932, her horse Trouble Maker won the Maryland Hunt Cup, regarded as America’s most challenging timber race, and in 1938, her horse Battleship, a son of Man o’ War, became the first American bred and owned horse to win the British Grand National Steeplechase. In 1929, Marion inaugurated the Montpelier Races and opened them to the public. Marion's legacy continues with the running of the Montpelier Races, a premier event on the National Steeplechase Association’s circuit, which is always held on the first Saturday in November.