According to the Federal Government Regional Planning Guidelines, the larger German city regions/agglomerations are `regional motors for growth for the regional development of the Federal Republic as a whole. However, their efficaciousness is increasingly hampered by the heavy burdens they have to bear'. (17) The main problems are the constant growth in private transport, harmful environmental impacts, difficulties with public utility services, `pronounced housing shortages, scarce building land, and generally rising prices'. (18)

    Among the most badly affected agglomerations are Berlin, Hamburg, the Ruhr District, the Cologne/Düsseldorf region, and Greater Munich, Greater Stuttgart, and Greater Frankfurt.

    A package of measures has been proposed to alleviate these burdens and to ensure the continued feasibility of these regions. If such measures are to be successful, however, two essential conditions must be met: first there must be an amelioration in regional coordination and cooperation, and second existing local authority financial equalization systems that are necessary must be further developed in accordance with this purpose.
 

    The Rhine-Main Basin situated at the centre of the Federal Republic of Germany is the third largest German agglomeration after the Rhine-Ruhr district and Berlin, and is regarded by many as the economic heart of the Federal Republic. In 1992 an EC study ranked it first in Europe in respect of economic power. (19)

    `From the functional space point of view, [the Rhine-Main area] is a unit, but administratively it is distributed over a number of jurisdictions, namely three Länder (Rhineland-Palatinate, Hesse, and Bavaria), thus falling under three regional policy regimes,' (20) although the greater part of the area lies within the South Hesse planning region (see section I.3). There is no common administrative organization for the area as a whole. Its spatial extension is not clearly defined. `Ballungsgebiet Rhein-Main', `Verdichtungsraum Rhein-Main', `Region Frankfurt', `Stadtregion Frankfurt-Offenbach' or `Aktionsraum Frankfurt' (21): each of these terms refers to a differently defined territory with different dimensions, population figures etc.

    More recent definitions describe the Rhine-Main area as a region with high functional interdependence located between the cities of Darmstadt (to the South), Friedberg (to the North), Aschaffenburg (to the East), and Mainz (to the West), with Frankfurt at the geographical centre.

    It is more and more difficult to give a precise, objectively well-founded delimitation of the region, or of most other agglomerations for that matter. Every relevant functional area or sphere of responsibility, from the labour and housing markets, to cultural and leisure infrastructure, mass transit, and sewage and refuse disposal covers a different territory. And each of these territories is subject to relatively rapid change.
 

    The Rhine-Main Basin is characterized by its geographically central position in transportation networks within the Federal Republic of Germany. It is the place where the supraregional axes of German and European rail and motorway networks cross, not to mention the Rhine and the Main waterways triangle. (22) The Rhine-Main Airport, situated to the Southwest of Frankfurt, links the region to all relevant international centres, being the second largest passenger airport in Europe after London Heathrow.

    Unlike the monocentrically structured regions of Hamburg, Munich or Berlin, the Rhine-Main area, with its more than three million inhabitants and approximately 1.6 million persons in employment (23) exhibits a polycentric structure, in which, however, the city of Frankfurt is clearly predominant thanks to its outstanding economic clout as well as its size (pop. in mid-1994: 664,000).

    Other higher order centres in the region are the two Land capitals of Mainz (pop. 184,000, Rhineland-Palatinate) and Wiesbaden (pop. 268,000, Hesse), as well as Darmstadt (pop. 140,000) and Offenbach (pop. 117,000). (24) Hanau and Rüsselsheim should also be mentioned, which, although not large cities, are nevertheless important regional employment centres.

    According to the 1992 Regional Planning Report, (25) the population of the cities and Gemeinden in the region has, after a period of decline, been increasing again since 1987 due to substantial in-migration. The number of people in employment has also been rising, especially in the services sector. This urbanization in the residential and employment fields is continuing. Communities close to and further away from central cities are becoming increasingly attractive as places to live. At the same time, there is a `relocation of manufacturing jobs, but also of logistical, distribution, and administrative functions to Gemeinden outside the central cities, accompanied by rising concentration of `high-quality' tertiary white-collar jobs in the higher order centres'. (26) The consequences of these developments are growing commuter flows, a continuous growth in road and traffic density, and a persisting demand for land for settlement purposes.
 

    With somewhat more than 660,000 inhabitants and an area of 250 kmē, Frankfurt is a relatively small city by international standards. However, its economic clout, based on specific historical preconditions, on the consequences of World War II, on its central position, and on its excellent transport and communications infrastructure, has lent the city a position of importance transcending the boundaries of Germany and Europe.

    Characteristic of Frankfurt's economy is `its strong orientation on the world market, the high degree of international interlinkage ... , an increasing concentration of top decision-makers (head offices, umbrella organizations etc.), the high share (more than 70 per cent) of the service sector, and (in comparison to other cities) the impressive degree of economic diversification'. (27) According to the 1987 census (VZ 1987) more than 600,000 gainfully employed persons (in a population then of some 620,000) earned just under DM 50 billion, the highest GDP per capita of all Federal German cities.

    The central economic factor in Frankfurt is the finance sector, which has decisively influenced the spatial structure and form of the city (high-rise development). More than 400 banks are represented in the city, of which over 60 per cent are foreign. The airport is considered to be almost as important, with more than 27 million passengers (1989) and 1.1 million tonnes of air freight turnover. Third in importance are the more than twenty trade fairs - for the most part international events - that are staged each year, and the more than 6,500 wholesale and retail firms established in the city, many of regional and supraregional importance.

    From as early as the seventies, persisting economic growth, a clear preference on the part of the most productive and hence solvent uses for the central city with resulting rises in rents and real property prices were accompanied by profound functional segregation processes - and in view of the narrow city boundaries - by growing functional interlinkage of the city with surrounding Gemeinden. Observers believe that Frankfurt is becoming more and more the centre of a `regional city' absorbing all the communities in its sphere of influence, which, although it does not exist on the political and administrative books, is nevertheless a reality.
 

    Although Frankfurt is the central city of the Rhine-Main region, the entire area cannot be considered as belonging to the Frankfurt sphere of influence because of the many regional centres, each of which has its own catchment area. (28) Representatives of the Frankfurt Planning Office regard the six Landkreise contiguous to the city and the county borough of Offenbach as falling within the Frankfurt tributary region. Every fifth employee from these Kreise works in Frankfurt; 82 per cent of all Hesse commuters come from these immediate environs.

    However, the relocation of businesses (out of the central city) and firm expansions as well as new establishments (under more favourable conditions as regards prices than in Frankfurt) have caused Frankfurt's share in the employment figures, increasing for the overall immediate region, to decline - from 67 per cent in 1960 to 61 per cent in 1987. `While the central function of Frankfurt continues to grow ... an increasingly significant proportion of company business is being done at locations in the umland.' (29)

    Whilst in the sixties and especially in the seventies the population of Frankfurt declined steadily (to far below 600,000), since the second half of the eighties it has been growing markedly as has also been the case in the surrounding communities. However, there are pronounced differences between population structures in the central city and its umland, with increasing indications of extensive social segregation:

		Every second household in Frankfurt is now a single-adult household; the average size of households in Frankfurt is 1.87; whilst the average size of households in the umland is 2.37. (30) Less than a quarter of all households contain three or more persons, whereas outside the city the figure is over 40 per cent.
		More than 20 per cent of all Frankfurt inhabitants are foreigners - with persisting rates of in-migration; in surrounding Gemeinden the figure is just under 10 per cent.
		The proportion of social welfare recipients is about twice as high in Frankfurt as in the umland - with the rate of increase also markedly higher in the central city.

    Since the eighties, local government finances have developed in opposing directions in Frankfurt and the surrounding Gemeinden. Whilst in Frankfurt the gap between income and expenditure has widened continuously and local government indebtedness has risen drastically, the debt position of many authorities in the environs has improved or deteriorated only slightly.

    The reasons given for the tight budgetary situation of the central city are, in addition to the Federal Government's policy of passing on expenditure, the recession, and the decline in revenues from business tax, as well as the costs of German unification, the functions and outlays that result from Frankfurt's special position as central city, and from which the entire tributary region benefits. These include:

		The construction, maintenance and management of numerous facilities in the cultural and leisure sectors, from opera and theatre to museums and libraries, the zoo and the Palm Garden. Although these facilities are used by the surrounding Gemeinden - every fourth visitor to a Frankfurt museum comes from the Rhine-Main area -, they are financed by the city alone. `Every theatre ticket that an inhabitant of a neighbouring town bought during the 1986/87 season in the Frankfurt municipal theatres was subsidized by the City of Frankfurt to the tune of DM 208 in the form of an operating costs grant.' (31)
		Expansion of mass transit systems, especially tramways and the underground railway system.
		Construction of park and ride facilities in the umland.
		The development of social welfare housing in surrounding communities.
		And finally the constantly rising welfare costs - also due to the special attractiveness of the large city for social outcasts and marginalized groups.

    The financial costs of Frankfurt's central-city function are at present borne alone by the city. At the same time, the distribution of tax revenues is shifting more and more from the central city to the umland. `Frankfurt's net income from taxes rose by 52 per cent between 1979 and 1988, while that of surrounding Kreise grew by 68 per cent'. (32) This negative development in income can be attributed to two major factors:

		Changes in social structures in the city and its umland, and the consequent differentials in revenues from population-related wages and income tax. Whilst the umland Gemeinden benefit from the in-migration of well-paid middle class residents (working in Frankfurt, living in the environs) the concentration of low-income strata in Frankfurt lies heavy on the central-city purse. Already by 1983, the average taxable income per taxpayer in Frankfurt had been overtaken by that in surrounding Gemeinden. The figure for Frankfurt was about DM 39,700, for the umland DM 41,000, and for the `wealthy' Hochtaunus Kreis over DM 51,000. (33) In umland Gemeinden in 1987, 30 per cent of the administrative budget came from the local authority share of wages and income tax, whereas in Frankfurt the figure was slightly over 11 per cent.
		Unfavourable developments in the city's principal source of income - employment-related business tax - consequent on the recession and economic structural change, and on business policy disadvantageous to the city and the city budget. This includes tax-reducing investment in East Germany and decisions to relocate business activities beyond the city limits. Such locational decisions in favour of umland Gemeinden benefit firms in several ways. The locational credit and image value of the big city are retained while the burden of rent and real property prices and business tax (owing to lower local tax rates) is reduced.
		The local authority financial equalization arrangements of Hesse that disadvantage Frankfurt. In 1992 Frankfurt received DM  124 per inhabitant, whereas cities like Wiesbaden and Kassel reaped between three and a half and four and a half as much. Even the well-off Hochtaunus Kreis received twice as much.

    `Whether, especially in the agglomerations, there are increasing disparities in local authority finance between the centres and their environs that are far from being compensated by local authority financial equalization payments' (34) is an issue that is continually tabled but has yet to find a satisfactory solution.