David Meyer, sociology, explains in The New York Times (AP), April 22, 2018
Louis DeSipio, Chicano/Latino studies and poli sci, via the Newburgh Gazette, April 19, 2018
Bernie Grofman, poli sci, via The Salt Lake Tribune
Research by Sarnecka, Stanford and Thomas, soc sci, via Maclean's, April 17, 2018