(The Smithsonian National Postal Museum via Flickr)But in the 19th and early 20th centuries, the national mail service was the country's beating heart of innovation.
An early airmail plane parked next to a U.S. mail truck.
The Village Tavern, by John Lewis Krimmel, depicts the tavern as mail hub, with a mail carrier (left) walking through the door and a desk for writing in the corner.
City letter carriers with handcarts used to collect and transport mail.
A row of one-man mail wagons used to collect mail from city mailboxes.
Workers at a New York City post office load cannisters of mail into pneumatic tubes.
Dog sleds transporting mail in Alaska.
A mail motorcycle in Washington, D.C.
New York City Postmaster Thomas G. Patten hands Lt. Torrey Webb a bag of letters for one of the first regularly scheduled airmail flights in the U.S.
Clerks sort mail inside the tight quarters of a Railway Post Office car.
The first Highway Post Office bus in Strasburg, Virginia.
A U.S. Navy Regulus I missile, containing mail, is fired from the USS Barbero for the first, and last, official missile mail experiment.
A carrier delivering mail in a right-hand drive van, similar to the ones seen on the road today.