Buffalo, N.Y./Sep. 14, 1901/Pan American Exposition. Machine cancel (Bomar B01-15C) tying 1¢ Pan-American on cover with Expo. label the Day that President William McKinley died, although the address is an add-on to the commemorative cover, it is addressed to the President of the Expo., Extremely Fine. Estimate  $75 - 100. $0 (Image)