1921 "William Penn" Special Airmail, Wash. - Phila. November 14th, postmark tying two different 1¢ Washington stamps on cover to Philadelphia Pa., Welfare Federation boxed receiving handstamp regarding flight, Very Fine, less than 50 covers where carried in each direction. Scott No. 498, 525. AAMC No. 149  Estimate $100 - 150. $0 (Image)