AM radios . . . FM was still in its infancy when I was growing up. Most folks were still tuning into AM stations.
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That one got me thinking... because I know FM mono was invented before WWII and stereo in the 50s... and Ive got some 50s and 60s vintage stereo gear with FM dials.
I went and looked it up on Wikipedia and it seems that FM stations didnt outnumber AM until 1978.. wow would have though it a lot earlier.