I grew up in Gdańsk, where almost everyone's came from somewhere else.
In the middle of the 1970s, I moved to Katowice, just on the west side of the old Prussian-Russian border. The Przemsza river defined the old border. I was surprised how often people I met asked me from what side of Przemsza I was from. Soon, I observed statistical noticeable cultural differences.
Now, living in the U.S., I observe many similar historically conditioned regional differences.
Nevertheless, congratulations on the comprehensive presentation.
Lastly, please read other comments, and slow down those flickering maps.