# CZ133 - 1939 20c Canal Zone - Pedro Locks After, Flat Plate Printing, unwatermarked, brown

CZ133 – 1939 20¢ Pedro Locks

With the building of Gatun Dam, the Chagres River valley between Gamboa and Gatun became Gatun Lake.  The dam was the largest earthen dam in the world at the time of its construction, and Gatun Lake the largest manmade body of water.

Gaillard Cut then extended Gatun Lake across the continental divide to the Pedro Miguel locks on the Pacific side where it, in turn, flowed into the Miraflores spillway and on to the Pacific Ocean.

The original plan called for one three-step set of locks at Gatun, one at Pedro Miguel, and a two-step set at Sosa Hill.  In late 1907, engineers decided to move the Sosa Hills locks further inland to Miraflores because it featured a more stable construction foundation and greater protection against military bombardment from the sea.

Each 110 by 1,000 foot lock chamber was built  in pairs to accommodate two lanes of traffic capable of traveling in either direction as needs warranted.  The Gatun Locks consist of three “steps” of chambers, Pedro Miguel has one, and two are at Miraflores, for a total of 12 chambers in all.

By the force of gravity alone, the design called for water to lift ships 85 feet above sea level to the surface of Gatun Lake, float them across the Continental Divide, and lower them again to sea level in the opposite ocean.

The first concrete for the lock system was laid at Gatun on August 24, 1909.  It took four years to complete the system.  Complicating the project was the relative newness of concrete, which presented an engineering challenge in terms of estimating measurements and ratios of water to cement.  In total volume of concrete, the work in Panama would not be equaled until the construction of the Boulder Dam in the 1930s.

In spite of the difficulties, the results were extraordinary.  The locks are regarded as the structural triumph of the Panama Canal and are a unique aspect of the waterway.  Even today, the concrete in the Panama Canal locks and spillways is in nearly perfect condition.

Canal Zone Stamps Chronicle America’s Rise as a World Power

If you’ve never collected Canal Zone stamps before, now’s the time to start.  These intriguing stamps are historic links to our nation’s past.  With Mystic as your collecting partner, it’s easy to own stamps documenting this remarkable American engineering feat!

With military assistance from the United States, Panama declared its independence from Columbia on November 3, 1903.  The Hay-Bunau-Varilla Treaty was negotiated, than ratified in Panama on December 2, 1903.  The United States followed suit on February 23, 1904, clearing the way for a long-anticipated canal project across the Panama isthmus.

Almost immediately, administrators began preparations for the tremendous influx of people who would eventually assemble to work on the project.  Faced with the knowledge that most of the work force would be imported to the region from America and Caribbean countries, authorities quickly established a postal service to serve their needs as well as those of the Canal Commission.

On June 24, 1904, postal service was established as part of the U.S. Department of Revenue under the supervision of the Treasurer of the Canal Zone, Paymaster E.C. Tobey.  On this day, post offices were opened in Ancon, Cristóbal, Gatun, Culebra, and Balboa.  Railroad station agents operated as postmasters.

A small supply of 2¢, 5¢, and 10¢ Panama stamps were overprinted “Canal Zone.”  Only ordinary mail was handled by the Canal Zone postal system.  Mail destined for Central and South America and the West Indies was turned over to the Panama postal service to be forwarded, while mail sent to the United States and its territories and possessions were sent to the U.S. aboard vessels departing for New York. 

Overprinted Panama stamps were in use for less than a month.  On July 18, 1904, they were replaced  by U.S. postage stamps overprinted “Canal Zone.”

In December of 1904, Secretary of War William Taft ordered the overprinted U.S. stamps to be withdrawn, and replaced them with overprinted Panama stamps.  Taft’s executive order was reversed in 1924, when overprinted U.S. stamps were placed in use again.

On October 1, 1928, the first permanent issue Canal Zone stamp was issued.  The 2¢ stamp featured Lt. Col. George W. Goethal, the Canal project’s chief engineer and first Canal Zone governor.

In 1929, the first Canal Zone Airmail stamp was issued and in 1941, a series of Officials were produced.  On October 25, 1978, the last Canal Zone stamp was issued.