Language dotmap of 1931 Poland
Back in the interwar period Poland was one of the most ethnically diverse countries in Europe. Minorities made up 31% of population. Ukrainians, Belarussians and Ruthenians were concentrated mostly in the East, Germans lived in the West and Lithuanians populated the northernmost counties. Poland has also a very large Jewish community, concentrated mostly in larger cities. Warsaw alone was home to over 300,000 Jews, making it the largest Jewish city in the world second to New York City only.
Kamień Koszyrski county in was the most non-Polish county, with just 7.05 percent citizens claiming speaking Polish at home, followed closely by Drohiczyn and Kosów counties with 7.06 and 7.16 percent population speaking Polish respectively, all three in Polesie Voivodeship. There were 68 majority-minority counties in Poland (out of 261) populated by 8.6 million people (or 27.1 percent of total population).
Ukrainian was the most common minority language, with 3.2 million speakers. Yiddish ranked second, with 2.5 million speakers.