An extensive literature links the rise of populist radical right (PRR) parties to immigration. We argue that another demographic trend is also significant: Emigration. The departure of citizens due to internal and international emigration is a major phenomenon affecting election outcomes via two complementary mechanisms. Emigration alters the composition of electorates but also changes the preferences of remaining voters left behind. Empirically, we establish a positive correlation between PRR vote shares and population loss at the municipality level across Europe. A more fine-grained panel analysis of precincts in Sweden demonstrates that the departure of local citizens raises PRR vote shares in the places left behind and that the Social Democrats are the principal losers from emigration. Elite interviews and newspaper analyses highlight that emigration produces grievances on which populists can capitalize and that established parties do not effectively address. Emigration and the frustrations it generates emerge as important causes of populist success.