I posted about German regional academic performance back in 2016.
The evidence seemed to indicate that German IQ was fairly uniform across Germany, once you took the immigrants out.
However, soon afterwards I got the following curious email from one Carolin:
I stumbled upon a few studies (one done by the German military, when there was still a mandatory draft), that put the regional differences at much higher values than a few IQ points. Basically, there were many regions, where the AVERAGE recruit was in the best/worst 10%, which would dwarf even the black-white-gap.
You can read the report here (I can’t read German so you’ll have to tell me the details): http://www.nachdenkseiten.de/upload/pdf/130218_weissintelligenzverteilung_laender_deutschland.pdf
Map of conscript test performance according to a 1998 study:
What I take to be some test administered in schools:
They also reference another school test carried out by Bertelsmann and published in the Deutsche Lernatlas around 2011: