Ghettos were established by Nazi Germany in hundreds of locations across occupied Poland after the German invasion of Poland. Most ghettos were established between October 1939 and July 1942 in order to confine and segregate Poland's Jewish population of about 3.5 million for the purpose of persecution, terror, and exploitation. In smaller towns, ghettos often served as staging points for Jewish and mass deportation actions, while in the urban centers they resembled walled-off prison-islands described by some historians as little more than instruments of "slow, passive murder", with dead bodies littering the streets. In most cases, the larger ghettos did not correspond to traditional Jewish neighborhoods, and non-Jewish Poles and members of other ethnic groups were ordered to take up residence elsewhere. Smaller Jewish communities with populations under 500 were terminated through expulsion soon after the invasion.
The liquidation of the Jewish ghettos across occupied Poland was closely connected with the construction of secretive death camps—industrial-scale mass-extermination facilities—built in early 1942 for the sole purpose of murder.Dwork, Deborah and Robert Jan Van Pelt,, W.W. Norton & Co., 1996. The Nazi extermination program depended on rail transport, which enabled the SS to run and, at the same time, openly lie to their victims about the "resettlement program". Jews were transported to their deaths in Holocaust trains from liquidated ghettos of all occupied cities, including Łódź Ghetto, the last in Poland to be liquidated in August 1944. In some larger ghettos there were armed resistance attempts, such as the Warsaw Ghetto Uprising, the Białystok Ghetto Uprising, the Będzin and the Łachwa Ghetto uprisings, but in every case they failed against the overwhelming German military force, and the resisting Jews were either executed locally or deported with the rest of prisoners to the extermination camps. By the time Nazi-occupied Eastern Europe was liberated by the Red Army, not a single Jewish ghetto in Poland was left standing. Only about 50,000–120,000 Polish Jews survived the war on native soil, a fraction of their prewar population of 3,500,000. , 1943. Jewish men with their hands up, surrounded by military units In total, according to archives of the United States Holocaust Memorial Museum, "The Germans established at least 1000 ghettos in German-occupied and annexed Poland and the Soviet Union alone." The list of locations of the Jewish ghettos within the borders of pre-war and post-war Poland is compiled with the understanding that their inhabitants were either of Polish nationality from before the invasion, or had strong historical ties with Poland. Also, not all ghettos are listed here due to their transient nature. Permanent ghettos were created only in settlements with rail connections, because the food aid was completely dependent on the Germans, making even the potato-peels a hot commodity. Throughout 1940 and 1941, most ghettos were sealed off from the outside, walled off or enclosed with barbed wire, and any Jews found outside them could be shot on sight. The Warsaw Ghetto was the largest ghetto in all of Nazi-occupied Europe, with over 400,000 Jews crammed into an area of, or 7.2 persons per room. The Łódź Ghetto was the second largest, holding about 160,000 inmates. In documents and signage, the Nazis usually referred to the ghettos they created as Jüdischer Wohnbezirk or Wohngebiet der Juden, meaning "Jewish Quarter". By the end of 1941, most Polish Jews were already ghettoized, even though the Germans knew that the system was unsustainable; most inmates had no chance of earning their own keep, and no savings left to pay the SS for further deliveries. The quagmire was resolved at the Wannsee conference of 20 January 1942 near Berlin, where the "Final Solution" was set in place.
The ghetto inhabitants – most of whom were murdered during Operation Reinhard – possessed Polish citizenship before the Nazi–Soviet invasion of Poland, which in turn enabled over 150,000 Holocaust survivors registered at CKŻP to take advantage of the later repatriation agreements between the governments of Poland and the Soviet Union, and legally emigrate to the West to help form the nascent State of Israel. Poland was the only Eastern Bloc country to allow free Jewish aliyah without visas or exit permits upon the conclusion of World War II. By contrast, Stalin forcibly brought Soviet Jews back to USSR along with all Soviet citizens, as agreed to in the Yalta Conference. Some Jewish populations remained in the ghettos after their destruction. The more prominent ghetto being the Warsaw ghetto. Many Jewish people were either too destitute or still surrounded by Germans to be able to leave the ghettos, this resulted in many of the ghettos inhabitants dying from harsh conditions such as exposure, lack of food, and diseases from being unclean. Another issue of the ghettos was where the displaced people who lived there would go next as refugees.
