Why was official racial domination enforced in South Africa and the United States, while nothing comparable to apartheid or Jim Crow was constructed in Brazil? Slavery and colonialism established the pattern of early discrimination in all three cases, and yet the postabolition racial orders diverged. Miscegenation influenced later outcomes, as did economic competition, but neither was decisive. Interpretations of these historical and economic factors were shaped by later developments. This article argues that postabolition racial orders were significantly shaped by the processes of nation-state building in each context. In South Africa and the United States ethnic or regional "intrawhite" conflict impeding nation-state consolidation was contained by racial domination. Whites were unified by excluding blacks, in an ongoing dynamic that took different forms. Continued competition and tensions between the American North and South or South Africa's English and Afrikaners were repeatedly resolved or diminished through further entrenchment of Jim Crow or apartheid. With no comparable conflict requiring reconciliation in Brazil, no official racial domination was constructed, although discrimination continued. The dynamics of nation-state building are then reviewed to explain variations in black mobilization and the end of apartheid and Jim Crow.