Congratulations to Casper, your version is correct. Dizma have a point as well. Beside of that I would like to write that PO doesn't run liberal policy, they calculate that this would be against party interest and of course masters in Brussels would be disappointed. Add their hidden disregard for the Catholic church and you will have  a typical European Christian Democrat party. Disgusting... 

This is very interesting. However, the entire German population was expelled in 1945 and replaced by Poles from the eastern parts of Poland which were ceded to the Soviet Union. Stalin made Poland shift to the west. Only the southeastern border (to Slovakia) is the same as it used to be before 1945, all other borders changed. Germans only remained in some parts of Silesia where they were needed for their expertise in coal mining. So I'd say it is not a question of cultural heritage. I can imagine two reasons for the clear dichotomy on the map:

1. The western part (German until 1918 or 1945) has always been more industrialised and thus wealthier, more educated and less rural. And in recent years, the development has been much higher in western Poland than in the eastern, rural areas. This is also due to geography. Eastern Poland is sparsely populated and far from European economical centres. You'll notice on the map that Warsaw follows the pattern of western Poland.

2. After the western areas were annexed to Poland in 1945, they were colonised (and rebuilt) by settlers from eastern Poland. So a kind of entrepreneur spirit may have origined in those years, an experience of achieving goals through organised work. The eastern areas were less destroyed, as far as I know, so they may not have needed to rebuild so much.

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On the map above we can not see the border of the Austrian (Austro-Hungarian) part of today's Poland (Galicia). The situation there is  similar to that in the former Russian part of Poland. You can see Galicia on  this map.