Modern-day Poland encompasses territory that was part of the pre-WWI German, Russian, and Austrian empires. And it seems that Poland’s recent election results partially track the separation between the formerly-German and the formerly-non-German parts of the country:
History’s impact can often be surprisingly long-lasting. It’s been a long time since taking midwestern agricultural products via train to Chicago and then by boat across the Great Lakes, across the Eerie Canal, down the Hudson, and to the port at New York was a major element in the American economy. But we still have two giant cities in Chicago and New York specifically because it used to be very important. I wouldn’t be surprised if the German-run bit of Poland was richer in 1918 than the rest of it, and that the differential has persisted since then. By the same token, we can expect the East Germany part of Germany to remain poorer than the West Germany part for a long time.