Air conditioning
Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by US inventor Willis Carrier. The introduction of residential air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States.
George Westinghouse
George Westinghouse Jr. (October 6, 1846 – March 12, 1914) was an American entrepreneur and engineer based in Pennsylvania who invented the railway air brake and was a pioneer of the electrical industry, gaining his first patent at the age of 19. Westinghouse saw the potential in alternating current as an electricity distribution system in the early 1880s and put all his resources into developing and marketing it, a move that put his business in direct competition with the Edison direct current system. In 1911 Westinghouse received the AIEE's Edison Medal "For meritorious achievement in connection with the development of the alternating current system."