What DISCOVERY led to the most American jobs? Why? And Who made it?

Question

Perhaps world-wide. HINT: autos, trains, planes, ships, rockets, bombs, Microsoft, weather reporting, laser surgery, lawn mowers, western movies,space suits, etc. .

Answer 1

The discovery of America itself by Christopher Columbus...probably...???

Answer 2

Hamburgers. Americans love hamburgers and with all the competition that means a lot of job. Who invented it? Why the "Hamburgler" of course.

Answer 3

How about electricity?

Answer 4

The printing press? Because so many people would be lost without having easy access to books.

Answer 5

I'm going to guess, the A/C system that Tesla brought about.