Geography and urban development of Dresden past 60 years has made Dresden the fourth largest urban area in Germany after Berlin, Hamburg, and Cologne. The most important river in Dresden is the Elbe river, the only navigable body of water to flow through the city. There are also a number of tributaries such as the river Weißeritz. The nearest German cities are Chemnitz (80 km to the southwest), Leipzig (100 km to the northwest) and Berlin (200 km to the north). The Czech capital Prague is about 150 km to the south; the Polish city of Wrocław is about 200 km to the east. There are
Accession of Hamburg to the German Customs Union (Zollverein) by Hamburg. Thus Hamburg consumers had lower prices than consumers within the union. The German imperial constitution of 1871 brought no change in the legal situation of Hamburg and Bremen. Article 34 (and related provisions) went into the new constitution. After Hamburg had agreed to the constitution of the North German Federation, negotiations were held between November 1867 and March 1868 on the size of the free area. It was agreed that this would cover the Hamburg urban area, but not the outlying areas, including Ritzebuttel, Bergedorf and the Vierland (which were a condominium with Lübeck until January 1868), Waldvörfer,