The area includes the cities of (from the west to the east) Duisburg, Oberhausen, Bottrop, Mülheim, Essen, Gelsenkirchen, Bochum, Herne and Dortmund. The cities of the area have grown into one large complex forming an industrial landscape of unique size, enclosing about 9 million inhabitants, thus building the third largest urban area in europe after Greater London and Paris. The area is often mistakenly perceived as one city because the borderlines between the individual cities are not drawn on many maps.
The area first grew during the Industrial Revolution, mainly basing its economy on mining coal. Nowadays, it is plagued by economic crisis as demand for coal has decreased. The area has diversified its industry, but it competes with cheaper foreign markets and the neighboring Rhine area, which is also in crisis.
The dialect of German spoken in this area is called Ruhrdeutsch. There exist no official Ruhrdeutsch spelling rules nor a dictionary, yet a notable amount of literature has been published in it (as well as many other spoken German dialects), including comics such as Asterix.