I believe the answer is c.1920. However, I could be wrong.
This question is based on opinion
you could say
I would join the republican party because i agree with how they reason
or you could switch to another party and have the same reasoning
The classic example of this divide is how, traditionally, history curriculums approach the Civil War.
While this is less the case today, 25-50 years ago, if you grew up in the South, you would have learned about the "War of Northern Aggression"
If you grew up in the North, you would have learned about the American Civil War and the South's history of slavery and the war to end the slavery.
"Traditional" History is often written by those that were victorious, so it is remarkable to see how in the modern era voices are being heard that would not have been traditionally heard.
A global society means that history is more nuanced with more perspectives present at the table of history.
But there is still a long way to go. Californians will spend lots of time learning about Sutters Fort while Pennsylvanians will learn about Fort Duquesne.
