Marijuana shops and red-light districts are, however, not to be found in every city, town and village in the Netherlands. Following the pioneering work of the social ecology of the Chicago school of the 1930s and 1940s, studies of the geography of crime have found patterns of crime to be unevenly spread across cities and regions (Evans & Herbert 1989). This is also true for the Netherlands, as has been indicated by the four issues of The Netherlands in Maps in this volume: