Photograph showing an operator preparing to feed a carrier holding about 500 letters into the transmitter for despatch through the tube from Brooklyn Post Office to New York General Post Office, a distance of about 1.75 miles. Pneumatic mail tubes (PMT) were first introduced in Philadelphia in 1893 and in New York City in 1897. They were usually eight inches in diameter and were used to carry mail in bulk between sorting offices. The system in New York covered about 27 route miles, and remained in use until 1953, by which time it was the last such system in operation.
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