The 18-cent Pedro Miguel Locks Cut–Before commemorative (Scott 132) was issued on August 15, 1939. It is part of two groups of eight ‘Before’ and eight ‘After’ views of important Panama Canal scenes or facilities such as the single step locks at Pedro Miguel. In this northward-looking view taken on June 3, 1912, the west chamber is the focus of attention, and in it we can see that construction of the lock gates is well under way. Each of these lock gates weighs about seven hundred tons and is seven feet thick. At the far sides are the lower reaches of the twin peaks that dominate the area. These masses of rock served to anchor the work done at Pedro Miguel.
The 18-cent stamp was most often used to cover the domestic ship rate on a registered letter, most frequently seen on mail originating at the Canal Zone Philatelic Agency (CZPA). Only some 39,000 of the 210,000 printed were sold, many for use on first day covers at the time of issue and retained by collectors for their albums. The remainders were pulled off sale on February 28, 1941, and burned on April 12.
First day covers by dozens of cachet artists both on the Isthmus of Panama and in the United States are recorded, and the 18-cent value is common in such usages. However, except for those CZPA covers mentioned above, it is very seldom seen in any capacity on a non-philatelic cover.