American Legion, flying the Munson Steamship Line's flag which had been allocated the ship for operation in fast passenger service to South American ports, left the Camden yards at five-thirty on the afternoon of 16 July 1921 for the one-day voyage to Hoboken, New Jersey with cabins filled with dignitaries.
By 1924 Aeolus and Huron had dropped off the New York-Rio de Janeiro-Montevideo-Buenos Aires route to be replaced by sister "535's" and .