The Paris Pneumatic Post 1866-1984

Many major cities had systems like this. Toronto's peaked before WW II, stretching over some five blocks from Front St. to Adelaide, with branches over to Yonge and the Royal York Hotel, reaching about a dozen buildings. They ran the tubes alongside the sewer pipes.

I wonder if the idea could make a comeback. Using computers, pneumatic packets could be routed automatically. Would cut down on all the delivery drivers! But a tube-based system would probably be too small to deliver anything besides paper mail.

Edit: The New York system was 7 inches in diameter and handled small parcels between two dozen post offices until 1954! Built by the Tubular Dispatch Company of NY.