Mason was the head of manufacturing at Maxwell-Chalmers under Walter P. Chrysler before moving to appliance manufacturer Kelvinator. Nash acquired Kelvinator in 1936, mainly to acquire Mason as president. Mason engineers the merger of Nash and Hudson into the new American Motors Corporation of which he becomes chairman of the board, president, chief executive officer and general manager. He dies just six months after engineering what was then the largest automotive merger in U.S. history.