Above is a postcard from the Sesquicentennial Exposition that was held in Philadelphia in 1926. The image on the postcard is of the United States Post Office pneumatic mail tube terminals at the General Post Office in New York. According to the information printed on the postcard, 5.000,000 letters were sent daily through underground pneumatic mail tubes in New York City.
Pneumatic tubes were used for mail in several large cities of the United States and Europe starting in the second half of the 19th century, but they were largely abandoned during the 20th century. The New York Post Office used the tubes for mail from 1897 to 1953. Pneumatic tubes were in the basements of post offices where postal clerks filled, sent, opened and emptied the cylinder containers that carried the mail through the network of tubes. The operators that sent and received the cylinders carrying the mail were sometimes called Rocketeers.
Mail was loaded into airtight cylinders that were propelled by compressed air. The cylinders used by the New York City Post Office could hold 500-600 letters. They were 24 inches long, 8 inches wide and weighed 21 pounds. Doors on each end of the cylinders locked by cam. (source: The Pneumatic Mail Tubes: New York's Hidden Highway And Its Development by Robert A. Cohen)
image source: National Postal Museum
The picture below shows a New York Post Office pneumatic tube circa 1914-1915 (source: Library of Congress)
Visit Sepia Saturday
For More Vintage Images