http://dx.doi.org/10.1287/inte.1110.0544 © 2011 INFORMS
Designing New Electoral Districts for the City of Edmonton
Sabanci School of Management, Sabanci University, Orhanlı-Tuzla, 34956 Istanbul, Turkey, email@example.com
Ozyegin University, 34662 Istanbul, Turkey, firstname.lastname@example.org
Centre for Excellence in Operations, University of Alberta, Edmonton, Alberta T6G 2R3, Canada, email@example.com
HEC Montreal, CIRRELT, Montreal, Quebec H3T 2A7, Canada, firstname.lastname@example.org
Every few years, the city of Edmonton, Canada must review and evaluate changes to its electoral district boundaries. The review process that was completed in 2009 resulted in modifying the district plan from a six-ward system with two council members in each to a single-member 12-ward system. The authors of this paper designed the redistricting plan. This paper describes the algorithm we applied to solve the problem and the decision support system we used. The algorithm is based on a multicriteria mathematical model, which is solved by a tabu search heuristic embedded within a geographic information system (GIS)-based decision support system. The resulting district plan meets districting criteria, including population balance, contiguity, compactness, respect for natural boundaries, growth areas, and integrity of communities of interest. This plan was formally approved as a city bylaw and used in the municipal elections in 2010. Key words: political districting; decision support system; GIS. History: This paper was refereed. Published online in Articles in Advance July 11, 2011.
he city of Edmonton, Canada is governed by a city council whose members are elected through a district-based municipal election system. In most North American cities, the elected representatives are from single-member districts, that is, each district elects a single representative to the legislative body based on the “winner-take-all” principle. However, until 2010 the Edmonton city council has comprised 12 councilors (http://en.wikipedia.org/wiki/ Edmonton_City_Council) elected under a system of six wards (see Appendix A); each ward elected two councilors to the city council. Edmonton was the only city in North America that did not have a singlemember district plan (Duggal 2009). Edmonton’s municipal electoral districts are designed based on a precise set of criteria. These criteria appear in city policy documents that support the bylaws governing the election process. The main 534
criteria are listed below. The city of Edmonton (2009) includes a complete list. —Population equality among districts: In accordance with the “one-person-one-vote” principle, it is desirable to create wards that are balanced in terms of population and number of electors. The total population and the total number of electors based on the last census are each divided by the number of wards to be created, and ward boundaries are designed to keep ward population and elector counts within 25 percent of the average. —Future growth: Wards must be created considering the areas of the city that are growing or declining most rapidly, and allowing the resulting wards to be in place for at least three municipal general elections before a major revision is enacted. This usually means that wards containing the fastest-growing areas have lower than average populations, whereas
Bozkaya et al.: Designing New Electoral Districts for the City of Edmonton Interfaces 41(6), pp. 534–547, © 2011 INFORMS
wards with the fastest-declining areas have above average populations. —Respecting community league boundaries: A community league is “an organization of community residents who represent their community at large in communication with a municipal government” (http:// en.wikipedia.org/wiki/Community_league)....