Abstract
We examine the impact of physical distance, language, and religion on Law of One Price (LOP) deviations across interwar Canadian and modern Nigerian cities. The data comprise monthly average retail prices for narrowly defined goods collected by national statistical agencies. We find that differences in the fraction of the city population sharing a common language and religion have a significant impact on LOP deviations. The impact of language differences is consistent with a recently developed theory in which both trade costs and differences in signal-noise ratios contribute to LOP deviations.