The Ostflucht (German: ['st?fl?xt], "flight from the East") was the migration of Germans, in the later 19th century and early 20th century, from areas which were then eastern parts of Germany to more industrialized regions in central and western Germany. The migrants originated in East Prussia, West Prussia, Silesia and Posen; they moved to provinces along the Rhine and Ruhr rivers. Most of the migrants were ethnic Germans, but many migrants to the Ruhr were of Polish ethnicity, later known as Ruhrpolen.
The United States, which had been the major destination of emigrants from the German East, lost much of its attraction when it stopped granting free land to settlers in 1893. At the same time, the Ruhr area prospered, leading to high demand for labor, especially in coal mining and heavy industries. This led to an East-to-West migration within the Kingdom of Prussia. Through 1907, 2,300,000 people emigrated from Prussia's eastern provinces (Pomerania, West Prussia, East Prussia, Posen, and Silesia), while only 358,000 migrated into these provinces. Among the emigrants were 600,000 Poles. This loss of workforce hit farms, which made up for this by calling in seasonal workers from further east. Berlin and Brandenburg in the same time gained 1,200,000 inhabitants, while the Ruhr area and surrounding provinces (Westphalia and Palatinate) gained 640,000 people.
At the same time, increased immigration into the eastern German regions by Poles from western Russia caused imbalances and upheavals there, especially in Upper Silesia.
The emigration of Germans, and the higher Polish birth rate in the eastern provinces caused concern among German nationalists. This led to some special measures: