Rochester, Minnesota was embraced between Chicago and Saint Paul on March 8, 1930. Previously, planes had followed the river (between La Crosse and Saint Paul). An alternate route diverted to Rochester from these points on this date, resulting in new directional flights from Chicago and Saint Paul.

This cover was carried on the Contract Air Mail Route 9 inaugural flight from Saint Paul, Minnesota to Chicago, Illinois and is listed in the Contract Air Mail Flights (CAM) Section of The American Air Mail Catalogue as 9E20.

On April 15, 2008, Delta Air Lines and Northwest Airlines announced a merger agreement. The merger of the two carriers formed what was then the largest commercial airline in the world, with 786 aircraft. Delta Air Lines' brand survived, while Northwest's brand officially ended in 2009.