The Post Office Department linked Contract Air Mail Routes 12 and 33 on August 1, 1931 using a spur route from Fort Worth via Wichita Falls to Amarillo.

This cover was carried on the inaugural Contract Air Mail Route 33 flight from Wichita Falls, Texas to Amarillo, Texas and is listed in the Contract Air Mail Flights (CAM) section of The American Air Mail Catalogue as 33N25.