After several delays, this more direct service to the Canal Zone got underway on December 3, 1951. The new Foreign Air Mail Route 5 route was flown by fast Constellation Clippers, Los Angeles to Guatemala City. The flight then continued over the existing route to Panama.

This cover was carried on the December 6, 1951 inaugural Foreign Air Mail Route 5 flight from Guatemala City, Guatemala to Los Angeles, California (where it was backstamped) and is listed in the Foreign Air Mail (FAM) Section of The American Air Mail Catalogue as F5-192.