Setting the scene
Propeller airliners still dominated long routes, but airlines wanted jets that could cross continents faster; Boeing risked its finances on a civilian jet derived from military tanker research.
What happened
The Boeing 707 first flew on December 20, 1957, from Renton, Washington; Pan American World Airways soon ordered the jet for transatlantic service, shrinking ocean-crossing times.
Why it still matters
The 707 ushered in the Jet Age for mass tourism and business travel, making intercontinental flight routine rather than exotic. Memorable detail: Boeing painted "707" on the tail because executives worried the public would not recognize the model number.
Background
Jet liners shrank ocean-crossing times.