 After her death in 1920, Ogden Mills continued to purchase the surrounding property, enlarging the acreage of the property to total over , the size of the mansion grounds at the time that it was given to the state of New York.In 1929, the property was passed on to their son, Ogden Livingston Mills and upon his death in 1937, on to his sister Gladys Mills Phipps.In 1938, Gladys Mills Phipps donated the house and of land to the state of New York as a memorial to her parents.