Despite increasing speculation and attention, as of yet insufficient empirical research has been conducted on the possibility of a political cleavage based on differences between Canadian inner cities and suburbs. This article sheds light on the potential existence of such differences by analyzing federal elections at the level of the constituency from 1945 to 1997. Results show that city-suburban differences in federal party voting did not become significant until the 1980s, and increased after this point, with inner-city residents remaining to the left of the rest of Canada in their party preferences while suburbanites shifted increasingly to the right in their voting patterns. The results obtained from regression analysis suggest that such a divergence cannot be reduced solely to differences in social composition, housing tenure, or region, and thus confirm that it constitutes a ‘true’ political cleavage. It is argued that intra-urban geography needs to taken into account in future analyses of Canadian political behaviour.