You might be surprised and interested why this envelope was stamped so many local post office stamps, There was totally stamped 30 ones. Such as Manila, Tokyo, Shanghai, Singapore, Hong Kong, Calcutta, Wellington, Auckland, Melbourne, Sydne, Bombay, brasil, Miami, Cape Town, Madras, Johnesburg...etc. which was taken 100 days with Air Tour 44,500 miles around the world.

It is an Atlas Sky Merchant Air Tour 100 days 44,500 miles, New York, NY on April 15, 1948 per right bottom square stamp.

The left bottom printed "American Air Mail Society, Atlas Sky Merchant Cover Committee, Damon Runyon momorial Cancel Fund, RKO Building --Room 3005, New York 20, NY