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.
Willis Bradley Haviland
Willis Hoag Haviland, a farmer, and his second wife, Hannah Wing Haviland, were first cousins once removed, which caused friction with the Quaker Meeting to which they belonged, ending in severance with the church. Hannah Wing Haviland's half-sister was Ann Elizabeth Button (27 Mar 1823 – 15 Mar 1849), wife of David Jay Haviland (29 Mar 1820 – 13 Aug 1868); they were the parents of Elizabeth R. Haviland (1845–1888) who would marry Duane Williams Carrier and have only child Willis Haviland Carrier in 1876, later the inventor of modern air conditioning technology. Willis Haviland Carrier was named after Willis Hoag Haviland, who after Elizabeth's father's death took care of her before she was married. (Willis Hoag Haviland was also Elizabeth's uncle-in-law.)