Migration Analysis as a Political Instrument The case of the Leiden and Bulb Regions in Randstad Holland

This paper explains how a relatively simple analytical spatial algorithm and a GIS visualization of inter-municipal migration patterns revitalized the negotiations for a formal merger (called Holland Rijnland) between six municipalities in the urbanized Leiden Region and ten municipalities in the adjacent rural Bulb Region, both situated in Randstad Holland. Though the regional housing market was just one of the negotiation topics, the political discussion around it almost stymied the entire merger. We discovered a lack of knowledge about three key questions: Would the new merger function as one housing market region within the broader context of Randstad Holland? Do the original two regions interact at all? Or do lower-order regions exist instead? We answered these questions with the aid of individual migration data from Statistics Netherlands and by applying a method called Intramax Clustering in the GIS Flowmap programme. We found that the intended merger is indeed a housing market region; that interaction between the two regions is limited; and that lower-order housing market regions do exist. These findings helped to restart the negotiations; since 2004 Holland Rijnland has been a fact.