Prepaid postcard of 4c showing a cargo ship passing through the Panama Canal.
First Day of Issue postmark at Cristobal - is a port in the Atlantic side of the Panama Canal. It is located on the western edge of Manzanillo Island and is part of the Panamanian city and province of Colón. Cristóbal Colón is the Spanish translation for Christopher Columbus, an explorer from Italy for whom these places were named.
Text Source: Wikipedia