 Here in central Illinois, it would seem obvious that once invented, air conditioning would have quickly spread to homes and offices. Yet the answer is no. It had to battle a major trend of early 20th century America, the open air movement. Many hygienists at the turn of the 19th century believed indoor air unhealthy because of respiration. They pictured large crowds of people spewing out toxic carbon dioxide. So the opposed air conditioning claiming it was something for a factory, not for the home. Air conditioning came from the textile industry. Its name came from yarn conditioning. That's where textiles are exposed to moist air so they can be easily stretched. In the early 1900s textile mills installed high-speed looms that produced tremendous heat and dried the air, which could no longer soften the threads. These brittle threads easily broke. To prevent this, the textile engineers invented air conditioning to control the humidity in the air. Air conditioning then spread quickly to other industries where humidity control was important. In high humidity, chewing gum wouldn't congeal. Chocolate gets a gray powdery coating from the fat rising to the surface and breaddose slimes and goes sour. The open air movement blocked the export of air conditioning from the factory, especially to schools. At that time, open air schools were popular for dupercular children and were being extended to all students. In the winter, the students wore coats, gloves and hats and were wrapped to their seats with special padded bags for insulation. And there was no mechanical ventilation in summer. So, blocked in homes, offices and schools, how did air conditioning take over our living spaces? Via growing cultural phenomenon, the cinema. A few brave theater owners tried air conditioning in the early 1930s and found it attracted patrons in droves. By 1940, 90% of all movie theaters had air conditioning. And once patrons realized they weren't dying from it, air conditioning spread to homes and offices. Now, of course, it's essential to every aspect of American life. Without air conditioning, there would be no microchips, no Dallas, Texas as a world financial center, and the National Hockey League's Phoenix Arizona coyotes would still be Canada's Winnipeg jets.