Can voters distinguish between national and international sources of economic variation, or do they arbitrarily reward (punish) governments for developments originating abroad? Extant research considers the electorate as a monolithic block. Yet, given what we know of voter sophistication, we should expect that only sophisticated and well-informed voters can correctly evaluate fluctuations in the domestic economy. In this paper I argue that cross-border commuters (CBC), by virtue of their simultaneous exposure to two national economies, present such a most likely case. I leverage the gradual increase of CBC in neighbouring Germany and France following a Swiss labour market refrom to study the effects of increasing regional economic integration on electoral support for the incumbent in all elections from 1990-2017 in France and Germany. Using a difference-in-differences approach I find that electoral support for incumbent governments, at the aggregate and individual level, increased in affected regions in France and Germany. This suggests that - contrary to my expectations - voters in these areas attributed their localised economic success to national incumbents' performance rather than the labour market reform in Switzerland. My findings hold important implications for the study of contextual economic voting and political accountability in contemporary Western democracies.