Inventor Willis Carrier was an engineer from the east coast (not the deep south as one might expect), who started out working for a heating company. In 1902, Carrier was given the task of decreasing the humidity in a printing shop where the intense heat was causing the inks to run and bleed.
While attempts to create cooling systems had been attempted many times before, none were very successful. But Carrier managed to solve the problem, inventing a mechanical humidity controller that passed air through a filter, then over coils containing a coolant (the same basic design used in air conditioners today).