The Province of Upper Silesia was a province of the Free State of Prussia from 1919 to 1945. It comprised much of the region of Upper Silesia and was eventually divided into two government regions called Kattowitz (1939–1945), and Oppeln (1819–1945). The provincial capital was Oppeln (1919–1938) and Kattowitz (1941–1945), while other major towns included Beuthen, Gleiwitz, Hindenburg O.S., Neiße, Ratibor and Auschwitz, added in 1941. Between 1938 and 1941 it was reunited with Lower Silesia as the Province of Silesia.

The Free State of Prussia was one of the constituent states of Germany from 1918 to 1947. The successor to the Kingdom of Prussia after the defeat of the German Empire in World War I, it continued to be the dominant state in Germany during the Weimar Republic, as it had been during the empire, even though most of Germany's post-war territorial losses in Europe had come from its lands. It was home to the federal capital Berlin and had 62% of Germany's territory and 61% of its population. Prussia changed from the authoritarian state it had been in the past and became a parliamentary democracy under its 1920 constitution. During the Weimar period it was governed almost entirely by pro-democratic parties and proved more politically stable than the Republic itself. With only brief interruptions, the Social Democratic Party (SPD) provided the Minister President. Its Ministers of the Interior, also from the SPD, pushed republican reform of the administration and police, with the result that Prussia was considered a bulwark of democracy within the Weimar Republic.