In general, the characteristics of sustainability indicators are strongly dependent on socioeconomic and regional structural features. Qualitative (success) factors, such as culture and governance, knowledge and understanding, political will, and resources and management, also play a part. In order to encounter the great heterogeneity of municipal conditions and general context for sustainable development at local level and to offer orientation, a municipal typology system was designed based on a modified typology from the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR).
The municipality types presented here correspond to a combination of the BBSR’s urban / municipal settlement types and districts and a typology extension or differentiation—also identified by the BBSR—that includes the categories “developing / stable / shrinking” towns, municipalities and districts.
The variance analyses conducted at the German Institute of Urban Affairs (Difu) on the basis of this typology showed that the structure and structural development of a municipality can contribute to the explanation of differences in sustainable development. Put in statistical terms: the degree variances of most SDG Indicators within one type of municipality are lower than the variances in the overall population of all cities, municipalities or districts.
In all, two typological classifications were made: town and municipality types, and county types. The variance analyses between town and municipality types and between county types reveal almost identical results, the main difference being that data for a maximum of 25 indicators were available at municipality level, whereas the data of a maximum of 50 indicators could be investigated at district level.
County-free cities occupy a special position, as they can be assigned to both a town and municipality type and a county type. On rare occasions the structural development of a county-free city (developing / stable / shrinking) can differ in both typologies for two reasons: firstly, the basic chronological order of town and municipality types (2012 - 2017) which led to the assignment of individual towns and municipalities is a year more up-to-date than that of the county types (2011 – 2016); secondly, smaller county-free cities and their surrounding counties were aggregated i.e. the structural development of these “county regions” was regarded as one unit.