Initial Air Mail Route 51 service was via Rocky Mount, Raleigh, Greensboro and Asheville, North Carolina to Knoxville from Norfolk. Storms prevented the complete service on November 1, 1940 the first westward flight terminating at Greensboro from which the first eastward flight was inaugurated the same day. 

Boeing 247D equipment provided the initial service. 

This cover was carried on the inaugural Air Mail Route 51 flight from Rocky Mount, North Carolina to Greensboro, North Carolina and is listed in the Contract Air Mail Flights (CAM) Section of The American Air Mail Catalogue as 51W2.

Pennsylvania-Central Airlines changed its name to Capital Airlines on April 28, 1948.

On June 1, 1961, Capital Airlines was formally merged into United Air Lines.