http://www.v-g-t.de/english/brd/module/m3/u2.htm

In Germany interregional migration began to increase considerably about 1850 when industrialization started. A strong emigration from the rural areas towards the cities of the developing industrial cores became the norm. Between 1860 and 1925 some 24 million people moved basically from rural areas towards the industrial centers and the cities, a movement that is known under the term of "Landflucht" (rural exodus). There were pull and push factors working together to stimulate this urbanization process. In rural areas, a great number of labour-force was set free due to new legacies (e.g. Bauernbefreiung = abolition of serfdom) and to new techniques in agriculture. At the same time an enormous demand for labour existed in the rapidly growing industry. Rural-urban migrations consisted mostly of short distance moves but to a remarkable extent also of long distance migrations. Especially the eastern provinces of Germany (e.g. East Prussia, West Prussia, Posen, Silesia, Pomerania) were important regions of origin from where many migrants moved West towards the rapidly developing industrial regions like Berlin, Saxony and the Ruhr Area. The percentage of immigrated Germans from the East added up to some 30 % of the inhabitants of the cities in the Ruhr Area. The demographic and social impacts were considerable. What can be observed though was a certain concentration in clusters by the immigrants according to their region of origin, their confession or other socio-economic parameters. Lutheran entrepreneurs (like Kirdorf, Grillo) had a tendency to recruit their workers from the protestant East Prussia, whereas Catholic entrepreneurs (like Thyssen, Klöckner) preferred to hire their workers from the catholic provinces of Posen or West Prussia.

Urban-rural migration can be observed for the first time during World War II, when people moved out of the bombed cities into the less affected rural areas. In Cologne, for instance, there were only about 100,000 people living in the city by the end of the war compared to more than 600,000 at the beginning. Rural areas were also the destination for the flows of refugees [2] and expellees from East Prussia, Pomerania and Silesia because the cities were widely destroyed. The Länder of Schleswig-Holstein, Lower Saxony and Bavaria had the greatest intake of these people from the East. Again, in many cases spatial concentrations [3] of people of the same origin occurred in order to create new neighbourhoods and communities by staying together as much as possible in this new environment. But this was a more temporary situation. It changed as early as the mid 1950s, when the so-called Wirtschaftswunder (economic miracle) began. Many of the former refugees now moved on from their temporary domiciles in rural areas towards the cities and the big industrial agglomerations (e.g. locations along the Rhine and the Ruhr rivers) in search of better jobs and living conditions.