The Ruhr Poles
A glance at the two-volume encyclopedia of surnames of Polish origin in the Ruhr area is enough to get an idea of how close the genealogical relationship between Germans and Poles is - especially in the Rhine and Ruhr regions. On the basis of telephone directories from 1994 to 1996 alone, the authors identified more than 30,000 Polish surnames in the Ruhr area. This does not take into account German variants of Polish surnames and name transformations, or Germanised forms of originally Polish surnames, not to speak of family members and persons with no telephone connection or with a telephone number hidden behind the individual telephone directory entries during the said period.
The background to this close relationship is made up of several westward migration phases from areas with an ethnic Polish population, or from a Polish state between the middle of the 19th century and the present day. The most comprehensive of these migrations took place in the Rhineland Westphalian industrial area between 1870 and the start of the 1920s. In contrast to overseas emigrations that took place at the same time and were also designated as migration processes, this migration movement, which was known under the heading "Ost- bzw. Landflucht" (migration from Eastern resp. rural Prussia), was an internal migration within Prussia and the German Reich: i.e. the emigrants were Prussian citizens who were free to choose their place of work and life on the basis of the Reich Law on Freedom of Movement passed in November 1867. According to calculations made by researchers on the basis of Prussian statistics, during this period up to half a million Polish-racial or Polish-speaking people emigrated from rural eastern provinces in Prussia to the Rhine-Ruhr industrial area. That said, the most recent studies and comparisons of individual emigration figures from certain regions (including Upper Silesia, as well as the inaccuracy and, at times, deliberate manipulation of Prussian statistics and the high fluctuation of immigration, repatriation and onward migration that is not reflected in these statistics), point to a considerably higher number of persons who were living and working in the Rhine and Ruhr around 1900, at least for on a temporary basis.
About one third of the migrants, for whom the term Ruhr Poles has established itself in research, came from each of the provinces of Poznan and East Prussia, above all from the Masurian provinces (Polish-speaking Protestants), and southern Warmia, which was also largely Polish-speaking but Catholic. In addition to the two largest groups, several tens of thousands of immigrants each came from West Prussia, Kashubia and the province of Silesia, especially from the southern part of the administrative district of Opole (Polish-speaking Catholic Upper Silesians). The main reasons for migration were economic. The population growth that gained momentum in the 19th century had led to overpopulation in the rural regions of origin. Moreover, these regions were industrially underdeveloped or not developed at all (with the exception of Upper Silesia). Above all they offered young men few job opportunities, poor living conditions and hardly any future prospects.
 Rymut, Kazimierz/Hoffmann, Johannes (eds.): Lexikon der Familiennamen polnischer Herkunft im Ruhrgebiet, 2 volumes, Kraków 2006, pages XXXV–XXXVI.
 cf. amongst others: Murzynowska, Krystyna: Die polnischen Erwerbsauswanderer im Ruhrgebiet während der Jahre 1880–1914, Dortmund 1979, pp. 25–26. Also other scholars like Witold Matwiejczyk and Valentina-Maria Stefanski, refer to Murzynowska's presentation and Prussian statistics.
 Skrabania, David: Keine Polen? Bewusstseinsprozesse und Partizipationsstrategien unter Ruhrpolen zwischen der Reichsgründung und den Anfängen der Weimarer Republik, pp. 45–47 (unpublished thesis, Bochum 2018, The thesis can be seen at Porta Polonica).
 The group of Ruhr Poles also included Masurians, whose specific characteristics mean that they will not be included in the rest of this text. The circumstances and causes of the Masurian migration process to the Rhine and Ruhr were very similar to those of the other Prussian eastern provinces. They, too, were a Polish-speaking and Slavic people who, although they had been politically integrated into the Kingdom of Prussia since the 17th century, retained their own characteristics even into the 20th century, for example with regard to Protestantism strongly interspersed with elements of Catholicism or their spoken dialect, an old Polish dialect. In the Rhineland-Westphalian industrial area, Masurians were often set apart from other Polish-speaking migrants as well as from the German-speaking majority society. At least partially, their religious denomination and a fundamental Prussian royalism facilitated their integration and assimilation in the Rhineland-Westphalian industrial area. However, two factors seem to have played a more significant role. Firstly, the agrarian, very sparsely populated and economically extremely weak Masuria offered hardly any opportunities to return and earn a living. Secondly, dozens of Masurian villages were de facto dissolved as a result of migration to the Rhine and Ruhr, and entire villages often suffered severe population losses, including preachers. Thus, it was practically impossible for many Masurians to return during or shortly after migrating. See Kossert, Andreas: Masuren. Ostpreußens vergessener Süden, Berlin 2001; Jasiński, Grzegorz: Mazurzy w drugiej połowie XIX wieku. Kształtowanie się świadomości narodowej, Olsztyn 1994.
 Kleßmann, Christoph: Polnische Bergarbeiter im Ruhrgebiet 1870–1945. Soziale Integration und nationale Subkultur einer Minderheit in der deutschen Industriegesellschaft, Göttingen 1978, pp. 24–27.