Second Polish Republic
City Population Voivodeship
1 Warsaw 1,289,000 Warsaw Voivodeship
2 Łódź 672,000 Łódź Voivodeship
3 Lwów 318,000 Lwów Voivodeship
4 Poznań 272,000 Poznań Voivodeship
5 Krakow 259,000 Kraków Voivodeship
6 Wilno 209,000 Wilno Voivodeship
7 Bydgoszcz 141,000 Poznań Voivodeship later Pomeranian Voivodeship
8 Częstochowa 138,000 Kielce Voivodeship
9 Katowice 134,000 Silesian Voivodeship
10 Sosnowiec 130,000 Kielce Voivodeship
11 Lublin 122,000 Lublin Voivodeship
12 Gdynia 120,000 Pomeranian Voivodeship
13 Chorzów 110,000 Silesian Voivodeship
14 Białystok 107,000 Białystok Voivodeship
15 Kalisz 81,000 Poznań Voivodeship
16 Radom 78,000 Kielce Voivodeship
17 Toruń 62,000 Pomeranian Voivodeship
18 Stanisławów 60,000 Stanisławów Voivodeship
19 Kielce 58,000 Kielce Voivodeship
20 Włocławek 56,000 Pomeranian Voivodeship
Demographics -- Largest cities in the Second Polish Republic
Poland 's population density in 1930 Contemporary map showing language frequency in 1931 across Poland ; red colour : more than 50% native Polish language speakers ; green colour : more than 50% native language other than Polish , including Yiddish , Hebrew , Ukrainian , Belarusian , Russian and less frequent others The Second Mountain Brigade of the Polish Legions in World War I officers establishing the Polish-Czechoslovak border near the summit of Popadia in Gorgany during the formation of the Second Republic , 1915
The Second Polish Republic, commonly known as interwar Poland or Poland between the Wars, refers to the country of Poland in the period between the First and Second World Wars (1918-1939). Officially known as the Republic of Poland (Polish: Rzeczpospolita Polska), the state was re-established in 1918, in the aftermath of World War I. The Second Republic ceased to exist in 1939, when Poland was invaded by Nazi Germany, the Soviet Union and the Slovak Republic, marking the beginning of the European theatre of World War II. In 1938, the Second Republic was the sixth largest country in Europe. According to the 1921 census, the number of inhabitants was 27.2 million. By 1939, just before the outbreak of World War II, this had grown to an estimated 35.1 million. Almost a third of population came from minority groups: 13.9% Ruthenians; 10% Ashkenazi Jews; 3.1% Belarusians; 2.3% Germans and 3.4% Czechs and Lithuanians. At the same time, a significant number of ethnic Poles lived outside the country's borders. When, after several regional conflicts, the borders of the state were finalized in 1922, Poland's neighbors were Czechoslovakia, Germany, the Free City of Danzig, Lithuania, Latvia, Romania and the Soviet Union. It had access to the Baltic Sea via a short strip of coastline either side of the city of Gdynia, known as the Polish Corridor. Between March and August 1939, Poland also shared a border with the then-Hungarian governorate of Subcarpathia. The political conditions of the Second Republic were heavily influenced by the aftermath of World War I and conflicts with neighbouring states as well as the emergence of Nazism in Germany.