This is the first known 2c Pan-Am Expo used on domestic mail.
The use of the 2c Empire State Express (Scott #295) is within the proper period.
U.S. postal issues were sold in the Philippines from July 30, 1898 to June 30, 1899,
and were valid for use until October 1, 1903. Manila October 13 arrival on reverse.

THE SECOND RECORDED 2c PAN-AM EXPO USED IN THE PHILIPPINES
The First Cover

EXTREMELY SCARCE