The technology to transmit color television signals was first developed in the 1920s, and all three of the major U.S. networks had switched to color in the 1960s. But in the mid-1970s, nearly half of American households still had black-and-white sets, which didn’t disappear completely from store shelves until the 1990s. What took so long, and how was the public persuaded to make the switch? – Public Books