Between 1949 and 1989, the city of Berlin and its surrounding districts were separated from each other. The Wall completely interrupted earlier economic and commuter relations between 1961 and 1989; in fact, it isolated West Berlin completely. In 1990, the developments characteristic of urban development in the Western world also started in the Berlin-Brandenburg region: deindustrialisation, suburbanisation and decentralisation. Soon after unification, joint efforts by the political authorities of the city and the surrounding state of Brandenburg started to control regional development and prevent the destruction of the landscape by urban sprawl. The main focus of this chapter is on the organisational arrangement of joint planning in a region embracing areas belonging to different states. This is an exceptional experiment in Germany, caused by the failure of the referendum on the unification of the city-state of Berlin and the state of Brandenburg.
Until the Second World War, Berlin was the capital of the Prussian state and of the whole country. Because Germany's national government was in favour of the development of its capital city - which had undergone a period of rapid and immense growth between 1870 and 1914 - there was a historically exceptional chance to reform its administrative boundaries. In 1920 an administrative reform (by law of the Prussian State) created the new area of Berlin, in the form it is today. This reform meant the incorporation of the surrounding municipalities (which had already reached the size of big cities) into Gross-Berlin (Big Berlin). Since then, Berlin has consisted of a large area, including lakes and forests - a much larger area than that ever covered by any other big city in Germany. In fact, at the time the new Gross-Berlin was more of a region than a city.
Between 1945 and 1990 there was no cooperation in regional development or planning between Berlin and its suburban surroundings, because the Iron Curtain divided this metropolitan region in two. The only sphere of cooperation, which began in the late 1970s, concerned the disposal of waste. Because of the spatial limitation of West Berlin, it was not possible to dispose of all the waste produced by such an affluent society. For East Germany this provided a good opportunity to