In this paper, I show that political opposition to immigration can arise even when immigrants bring signi…cant economic prosperity to receiving areas. I exploit exogenous variation in European immigration to US cities between 1910 and 1930 induced by World War I and the Immigration Acts of the 1920s, and instrument immigrants' location decision relying on pre-existing settlement patterns. Immigration increased natives' employment and occupational standing, and fostered industrial production and capital utilization. However, despite these economic bene…ts, it triggered hostile political reactions, such as the election of more conservative legislators, higher support for anti-immigration legislation, and lower public goods provision. Stitching the economic and the political results together, I provide evidence that natives'backlash was, at least in part, due to cultural di¤erences between immigrants and natives, suggesting that diversity might be economically bene…cial but politically hard to manage.