Answer: Pneumatic Tubes

Starting in 1897, New York City enjoyed some of the fastest intra-city mail delivery of any metropolitan area, all thanks to the installation of high-speed pneumatic tubes beneath the city. These tubes, originally installed only between two post offices but quickly expanded to encompass the entire city with 27 miles of tubing, could carry 600 letters each at speeds of up to 35 miles per hour.

The tube system delivered mail all the way into the 1950s when, in 1950, construction on the Brooklyn Bridge took a line out of commission. While the repair work laid the line dormant, city officials began evaluating the cost of the tube delivery system. By 1953, after determining that it was no longer economically feasible to run the enormous system, the pneumatic tube system was decommissioned.