With no US register in place, the US Post Office assigned its own aircraft serials and many DH.4s were in the 60 to 110 range. The name Ak-Sar-Ben is Nebraska reversed; this airfield was funded by the so-called Knights of Ak-Sar-Ben. Photo dated 'circa 1927' by the Smithsonian's National Postal Museum, but in fact the mail service moved to Fort Crook in 1924. The first mailplane, DH.4 No 105, arrived at Ak-Sar-Ben Field from Chicago on 5 January 1920. At that time the hangar carried a smaller sign saying 'Post Office Dept'. Photo from: Smithsonian Institution