The fact that we listen to virtually all our music in stereo these days goes back to a guy named Sidney Frey, the founder and president of a company called Westrex. Westrex made machines that cut master plates from which vinyl records were pressed. After demonstrating the first stereo disc In December 1957, he offered a free copy of that disc to anyone in the industry who wrote to him on company letterhead.
Dealers everywhere got discs and began to demonstrate them to customers who went crazy for stereo. Gear started flying out the door and the price of the special needles needed to play these new records fell nearly 90% (from $250 each to about $30).
By March 1958, stereo recordings of regular records started appearing in stores. Ten years later–1968–all the major record labels stopped selling mono records and went 100% stereo. More on stereo next time.