Division of Posen, Prussian Silesia, West Prussia and East Prussia after World War I From province: Area in 1910 in km2 Share of territory Population in 1910 After WW1 part of: Notes West Prussia 25,580 km2[17] 100% 1.703.474 Divided between: to Poland 15,900 km2[17] 62% [18] 57%[18] Pomeranian Voivodeship [Note 2] to Free City Danzig 1,966 km2 8% 19% Free City of Danzig to East Prussia (within Weimar Germany) 2,927 km2 11% 15% Region of West Prussia [Note 3] to Germany 4,787 km2 19% 9% Posen-West Prussia[19] [Note 4] East Prussia 37,002 km2[20] 100% 2.064.175 Divided between: to Poland 565 km2[21][22] 2% 2% Pomeranian Voivodeship (Soldauer Ländchen)[23] [Note 5] to Lithuania 2,828 km2 8% 7% Klaipėda Region to East Prussia (within Weimar Germany) 33,609 km2 90% 91% East Prussia Posen 28,992 km2[20] 100% 2.099.831 Divided between: to Poland 26,111 km2[17] 90%[18] 93%[18] Poznań Voivodeship to Germany 2,881 km2 10% 7% Posen-West Prussia[19] [Note 6] Lower Silesia 27,105 km2[25] 100% 3.017.981 Divided between: to Poland 526 km2[21][26] 2% 1% Poznań Voivodeship (Niederschlesiens Ostmark)[27] [Note 7] to Germany 26,579 km2 98% 99% Province of Lower Silesia Upper Silesia 13,230 km2[25] 100% 2.207.981 Divided between: to Poland 3,225 km2[17] 25% 41%[17] Silesian Voivodeship [Note 8] to Czechoslovakia 325 km2[17] 2% 2%[17] Hlučín Region to Germany 9,680 km2[17] 73% 57%[17] Province of Upper Silesia TOTAL 131,909 km2 100% 11.093.442 Divided between: to Poland 46,327 km2 35% 35% Second Polish Republic [Note 9] to Lithuania 2,828 km2 2% 2% Klaipėda Region to Free City Danzig 1,966 km2 2% 3% Free City of Danzig to Czechoslovakia 325 km2 0% 0% Czech Silesia to Germany 80,463 km2 61% 60% Free State of Prussia