American Airlines, then the largest airline in the United States (and second largest airline in the world after the Soviet Union's Aeroflot) created a bold, new technology to book flight reservations.

They called it the "electromechanical reservisor", and it was the first machine of its kind.

Before the reservisor, American Airlines employees booked all reservations by hand using index cards and lazy susan filing systems.

Needless to say, the manual system was prone to substantial human error, and airline executives were keen to automate the process.

They went through several iterations of the technology until, in 1964, they completed the largest non-government data processing network in the world.

It was called Semi-Automatic Business Research Environment, or SABRE.

With its IBM 7090 mainframes, the system was able to process tens of thousands of tickets per day, pushing up-to-date seat inventory to more than 1,500 ticketing agents across the country.

Within the next several years, most major airlines (including Delta and United) followed with their own booking systems.

Fast forward a few decades, and those systems from the 1960s still form the core technology of airline reservation systems today.