Ruhr

The Ruhr (/ˈrʊər/ ROOR; German: Ruhrgebiet [ˈʁuːɐ̯ɡəˌbiːt] ^ⓘ, also Ruhrpott German pronunciation: [ˈʁuːɐ̯pɔt] ^ⓘ), also referred to as the Ruhr Area, sometimes Ruhr District, Ruhr Region, or Ruhr Valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 1,160/km² and a population of over 5 million (2017), it is the largest urban area in Germany and the third of the European Union. It consists of several large cities bordered by the rivers Ruhr to the south, Rhine to the west, and Lippe to the north. In the southwest it borders the Bergisches Land. It is considered part of the larger Rhine-Ruhr metropolitan region of more than 10 million people, which is the third largest in Western Europe, behind only London and Paris.

The Ruhr cities are, from west to east: Duisburg, Oberhausen, Bottrop, Mülheim an der Ruhr, Essen, Gelsenkirchen, Bochum, Herne, Witten, Hagen, Dortmund, Hamm and the districts of Wesel, Recklinghausen, Unna and Ennepe-Ruhr-Kreis. The most populous cities are Dortmund (with a population of approximately 612,065), Essen (about 583,000) and Duisburg (about 497,000).

In the Middle Ages, the Hellweg was an important trade route from the region of the Lower Rhine to the mountains of the Teutoburg Forest. The most important towns of the region from Duisburg to the imperial city of Dortmund were concentrated along the Hellweg from the Rhineland to Westphalia. Since the 19th century, these cities have grown together into a large complex with a vast industrial landscape, inhabited by some 7.3 million people (including Düsseldorf and Wuppertal, large cities that are nearby but officially not part of the Ruhr area).

The Ruhr area has no administrative centre; each city in the area has its own administration, although there is a supracommunal Ruhr Regional Association [de] institution in Essen. For 2010, the Ruhr region was one of the European Capitals of Culture.

The 1911 edition of Encyclopædia Britannica has only one definition of "Ruhr": "a river of Germany, an important right-bank tributary of the lower Rhine". The use of the term "Ruhr" for the industrial region started in Britain only after World War I, when French and Belgian troops had occupied the Ruhr district and seized its prime industrial assets in lieu of unpaid reparations in 1923. In 1920, the International Labour Office published a report entitled Coal Production in the Ruhr District. In 1923, the Canadian Commercial Intelligence Journal, Volume 28, Issue 1013, includes the article, "Exports from the Ruhr district of Germany". In 1924 the English and American press was still talking of the "French occupation of the Ruhr Valley" or "Ruhr District". A 62-page publication seems to be responsible for the use of "Ruhr" as a short form of the then more common "Ruhr District" or "Ruhr Valley": Ben Tillett, A. Creech-Jones and Samuel Warren's The Ruhr: The Report of a Deputation from the Transport and General Workers Union (London 1923). Yet "The report of a deputation from the Transport and General Workers' Union which spent a fortnight examining the problems in the Ruhr Valley", published in The Economic Review, Volume 8, 1923, is still using the traditional term. In the same year, "Objections by the United States to discriminatory regulations on exports from the occupied region of the Ruhr" was published in Papers Relating to the Foreign Relations of the United States.

The 1926 Encyclopædia Britannica, in addition to its article on the river Ruhr, has a further article on "RUHR, the name given to a district of Westphalia, Germany". Thus the name "Ruhr" was given to the region (as a short form of "Ruhr District" or "Ruhr Valley") only a few years before the publication of this edition of the Encyclopædia Britannica. Even after World War II, the term "Ruhr" may not have been in general use for the region: it was defined in Documents on American Foreign Relations (1948): "For the purposes of the present Agreement: (i) the expression 'Ruhr' means the areas, as presently constituted, in Land North Rhine–Westphalia, listed in the Annex to this Agreement." However, Lawrence K. Cecil and Philip Hauge Abelson still write in 1967: "In the first place, the average person uses the term 'Ruhr' indiscriminately as the Ruhr River or the Ruhr district, two entirely different things. The Ruhr River is only one of half a dozen rivers in the Ruhr district, in addition to the Rhine. The Rhine itself runs through the heart of the Ruhr district." According to Merriam Webster's Geographical Dictionary, a standard reference on place names around the world, the name "Ruhr" refers to the river. The name preferred for the region in this dictionary is "Ruhrgebiet", followed by "Ruhr Valley".

The urban landscape of the Ruhr extends from the Lower Rhine Basin east to the Westphalian Plain and south to the hills of the Rhenish Massif. Through the centre of the Ruhr runs a segment of the loess belt that extends across Germany from west to east. Historically, this loess belt has underlain some of Germany's richest agricultural regions.

Geologically, the region is defined by coal-bearing layers from the upper Carboniferous period. The coal seams reach the surface in a strip along the river Ruhr and dip downward from the river to the north. Beneath the Lippe, the coal seams lie at a depth of 600 to 800 metres (2,000 to 2,600 feet). The thickness of the coal layers ranges from one to three metres (three to ten feet). This geological feature played a decisive role in the development of coal mining in the Ruhr.