We exploit a population resettlement program of ethnic minorities in Malaysia to identify long-run effects of interethnic proximity on economic and political development. From 1948 to 1951, the colonial government moved 500,000 rural Chinese into hundreds of isolated, mono-ethnic camps. In ethnic majority Malay communities adjacent to these camps, we find greater economic prosperity and lower vote shares for the ethno-nationalist Malay party. Effects are stronger in areas with historical, interethnic economic complementarities. Primary survey data suggests that trust-building and social integration were key channels. Our findings highlight the importance of persistent, localized contact in the co-evolution of economic and political development.