US season-change dates (any season-season change) can range from the 19th - 21st due to the fact it's determined AT the Prime Meridian. And I distinctly recall one change (Eastern Time) that took place on the 22nd... but do not ask me which season or the year. But it was the 22nd.
Using a wall calendar: you have to make note of where that calendar's intended-use country is located. Not EVERY calendar printed is for use in the US. Amazon gets them from all over the world and I've had one from Australia (which may account for the 22nd mentioned above???) and another from South Africa (also may account for 22nd... being east of Prime Meridian).
I remember it being the 22nd one year also. Good to know that it can shift and why. thanks!
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