High-Resolution Mapping of World’s Electoral District Boundaries

• In Event: Poster Session: Posters in Political Methodology

Abstract

The paper presents a novel dataset, with high-resolution GIS maps of the boundaries of the electoral districts (past and present) used in more than 1300 elections held in over 160 countries. By high-resolution we mean boundaries that accurately and correctly display over streets, rivers, blocks’ boundaries and other low-level mapping details when zoomed-in. To make this dataset possible, we leverage three key aspects of electoral district boundaries seldomly emphasized. First, many electoral districts around the world are coterminous to mixtures of different levels of administrative or statistical divisions of a country (provinces, cities, neighborhoods, census blocks, etc). Second, when that is not the case, they nearly always at least share large parts of their boundaries with administrative or statistical divisions. Third, even in countries where electoral districts are geographically local and change often, relevant parts of their boundaries are stable over time. Those properties dramatically diminish the amount of manual vectorization required to reconstruct their GIS boundaries. The paper also discusses and exemplifies the array of techniques we employed with those properties in mind . Nearly all countries that ever had any contested election (i.e. with 2+ competing parties) have at least their most recent elections included, but in most cases earlier elections are also present. This includes, for example, the majority of the contested elections held in Belgium, Canada, France, Germany, Italy, Portugal, Russia, Spain, US and UK; most elections held in Latin America since 1945 and the majority held since 2000 in East Europe, Africa and Asia. In the end, all boundaries have been recreated following strictly official information, legislation and/or official map images. The vast majority are high-resolution boundaries created starting from official GIS administrative or census maps, and carefully manually adjusted or vectorized as needed. Even in the case of historical boundaries, we re-utilize parts of more current official boundaries and manually alter only what is required to account for the over-time changes. For mere 10 countries we can only approximate boundaries roughly and only 25 countries are still entirely missing – if we count as Not Applicable those that either never had any Lower Chamber election (e.g. Oman, Saudi Arabia, uninhabited areas), never had one with more than a single contesting party/group/individual (e.g. Eritrea, North Korea), did not have one in more than 50 years (e.g. Cuba, Laos) or had some but not using geographically defined electoral circumscriptions (e.g. Libya, Sudan). Hopefully this dataset will open doors for a variety of novel research venues. To illustrate its potential, we use the data to show how several countries that are either authoritarian or are known to host severely fraudulent elections, have nonetheless seen dramatic levels of gerrymandering to their electoral districts’ boundaries over the years.

Author

• Fabricio Vasselai, University of Michigan, Ann Arbor