I’ve never heard of anything like it, that is a massive reversal of a huge national voting block, how did they all get the message at the same time and what was the message that was so clear to all of them at the same time?
There was no gradual shift, no growing awareness, no shifting perceptions, just a big BOOM and they all switched.
Perhaps it was the power of the “Fireside Chat” over the radio.
Imagine what would happen if everyone switched to the internet and the internet was Republican only. FDR’s Fireside Chat may have been huge for the time.