UC Santa Barbara

When deciding where to draw the boundaries for electoral districts, officials often strive to ensure that communities of interest are not split up but kept together within a single district. What exactly constitutes a community of interest is somewhat vague, with legal and academic sources describing either a thematic region with shared demographic and land use traits or a cognitive region that is meaningful to people and commonly agreed upon. This research seeks to identify communities of interest at the sub-city level in both the thematic sense—by clustering Census tracts and land parcels according to classes of important variables—and the cognitive sense—by surveying residents about the location and extent of their community and finding areas of highest agreement. Then the degree to which the two senses of communities overlap is assessed; the more overlap, the more evidence there is that the two definitions correspond closely. Finally, the amount of overlap between the different communities and existing electoral districts is determined, to see which of the two types receives more attention from boundary drawers. The study finds that the two types of communities of interest correspond relatively well, and that the thematic type corresponds with the electoral districts better than the cognitive type.