Aviation Meet postal card
Crowds swarmed the field at the Driving Park Aviation Exhibition, held at Altoona, Pennsylvania, on May 18, 1912, preventing pilot Walter Brookins from making his scheduled flight. Brookins himself canceled the flight, for which 1,200 pieces of mail had been prepared. A special postmark device had canceled each piece. An example of the postmark appears here on a postal card addressed to Mr. J. Russell Hartman. A magenta circular postmark with seven wavy killer bars cancels the 1-cent McKinley indicia. It reads, "AERIAL POST OFFICE NO. 1 / ALTOONA, PA / MAY 18, 1912."
The Post Office Department designated this route as No. 610,001.