In 1897, a year when mail was still largely delivered by horse and wagon, construction began on an innovative scheme beneath the streets of Philadelphia. Using an intricate network of compressors and metal pipes, the new system could shoot a capsule holding a few hundred letters across a city in several minutes, far faster than a postman could get it there. The investor in this new technology wasn't some kind of delivery startup, the FedEx or UPS of its day. It was the U.S. Post Office.
Behind the experiment was Postmaster General John Wanamaker, who was inspired by Paris, London, and other European cities that were trying out pneumatic posts. It seemed a natural fit for America's growing metropolises, where mail was hauled by horse cart and carried on foot. Wanamaker had the sense not to try to concoct such a system in-house, since the agency had no such expertise. So he did something clever: He called for private proposals to build pneumatic tube systems.