AM Stereo
AM stereo came in around the end of the '70s. I remember a couple of the AM stations where I grew up started broadcasting in stereo in the early '80s, but it was kind of a moot point because nobody had an AM stereo receiver. I remember thinking at the time, who wants to listen to static in stereo? And of course, in the '90s, most AM stations had switched their format to news/sports/propaganda talk, with little or no music being played, so what was the point?