It's true that Las Vegas owes a portion of its growth to air conditioning.
It's also true that people lived through hot summers around the globe for thousands of years before 23-year-old Willis Haviland Carrier, waiting for a train on a foggy night in Brooklyn in 1902, solved the problem of temperature and humidity control in the printing plant where he was a mechanical engineer by coming up with his Rational Psychrometric Formulae (which stands to this day as the basis for all fundamental calculations for the air-conditioning industry).
For example, exactly when the first human discovered an evaporative cooling effect after exiting a lake or river on a hot day, no one can know. But ancient Egyptian aristocrats circulated water through the walls of their houses to cool them. In medieval Persia, a sophisticated system of open courtyard pools (rainwater collected in cisterns) and wind towers (to direct airflow over the cisterns) cooled buildings during the height of the scorching summers.
None other than Leonardo da Vinci is believed to have been the first to use a mechanical air cooler, when he rigged a hollow water wheel with a passage to guide the cooled air from the water wheel to a bedroom in the house. As the water moved from the outer edge toward the center of the wheel, it compressed the air and forced it through the passage into the cooled room.
In the early days of Las Vegas, locals did everything they knew how to beat the summer heat. They hung wet sheets around porches and on roofs and slept between them. In fact, a few people came down with pneumonia in the summer after wrapping themselves in wet sheets and sleeping in front of fans.
Around the same time, direct air coolers were evolving. Electric fans forced air over wooden frames covered with wet cloth. As more electrical appliances were developed, recirculating pumps were incorporated into the designs. Finally, in 1916, the first so-called swamp cooler was installed in the Adams Hotel in downtown Phoenix; it used two-inch excelsior pads, sandwiched between chicken wire and nailed to the cooler frame, to retain the water cooled by fans. Goettle Brothers Incorporated began mass producing swamp coolers in the 1930s, using Emerson Electric Company integrated motor-and-fan units.
In the meantime, compressed-air technology was also evolving. As far back as the 1820s, British inventor Michael Faraday was compressing and liquefying ammonia to chill air. Twenty years later, a Florida physician, Dr. John Gorrie, employed Faraday’s compressor technology to turn water into ice for the first time, which he used to cool the air in his hospital.
The earliest commercial applications of air conditioning were used for industrial processing rather than personal comfort. Willis Carrier cooled the air in his printing plant to maintain consistent paper dimensions. Film, meat, textile, pharmaceutical, tobacco, and many other industries clamored for air conditioning to control the temperature and humidity levels in manufacturing facilities. It wasn’t long until the technology was applied for human comfort as well: The Carrier Company (formed in 1915) installed a/c in the J.L. Hudson Department Store in downtown Detroit in 1924, creating an overnight sensation. Quickly, the Rivoli Theater in New York attracted droves of movie-goers seeking a little relief from the heat. Finally, the first residential a/c units were manufactured by the Carrier Company in the late 1920s.
Which, finally, leads us air conditioning in Las Vegas. The Apache Hotel, located on Fremont Street between Second and Third (now Binion’s), was the first Las Vegas lodging house to air-condition its lobby; it also introduced the "curtain of cool" concept when it engineered a continuous flow of cold air that blasted out of vents in the floor at the entrance to the lobby, keeping the hot air out and the cold air in and bathing patrons in a/c as they stepped inside. Locals filled the hotel lobby to escape the blistering summer heat.
The first hotel to air-condition its rooms was also the first hotel on the incipient Las Vegas Strip: Thomas Hull’s El Rancho Vegas, which opened in 1941. The entire property was air-conditioned (go to http://gaming.unlv.edu/centennial/web/0100_0081_ElRanchoVegas.jpg to see the proud claim of "100% Air-Conditioned" on the main sign to the building) and its cost was built into the room rates. Less than 10 years later, central air conditioning was standard in every hotel built, and has been ever since.
