1928 PITTSBURGH, PENN. On February 28 1928 the Clifford Ball Line flight from Pittsburgh to Cleveland, Ohio, crashed in the Monongahela River. This registered envelope to Los Angeles has a 20c stamp and another stamp was washed off in the accident. Posted at Newark FEB 14, it has a Pittsburgh 15 FEB backstamp and Los Angeles 18 FEB arrival cancels. An explanatory label, printed at Pittsburgh, accompanied the envelope and on arrival a violet two line ‘Received in Bad Condition / Los Angeles CA Post Office’ h/s was also applied. (Sanford 280215)