Something of a change today - WW1 U.S Forces.
A plain cover cancelled and mailed with machine PORTLAND MAR 3 1919 datestamp to the 89th Aero Sqn Amer E.F France. At this time the Sqn along with the 88th Aero Sqn was being disbanding and left France in June. The cover has been returned to the U.S. with the cachet RECEIVED CHELSEA TERM BPO From A.E.F. dated Apr 18 and reverse shows HEMPSTEAD N.Y. Mill Branch Apr 23 datestamp.
The squadron was first activated as the 89th Aero Squadron at Kelly Field, Texas during World War I. It deployed to France in 1917, where it constructed airfields and trained observers, In 1918 it briefly trained as an observation unit, but the unit did not move to the front before the Armistice. After the German surrender it served with the 4th Corps Observation Group (Third Army) at Trier Aerodrome.