Between 1942 and 1945, more than 32,000 male migrant workers were transported to the Brazilian Amazon from the country's Northeast, in the largest state-sponsored relocation of free labor in Brazilian history. These men were charged with supplying the United States with latex tapped from wild rubber trees, as part of a wartime campaign underwritten by the U.S. government. 1 This essay investigates how notions of gender shaped the formulation of the wartime migration project, the formation of regional labor markets, and the historical experiences of the migrants.Interregional migration is a key factor in understanding major changes in late-twentieth-century Brazil, including industrial development, proletarianization, frontier expansion, shifting patterns of political participation, and the transformation of individual subjectivities. Between 1960 and 1980 alone, 29.4 million Brazilians -a population larger than most Latin American nations -migrated from the countryside to the cities, in the process transforming Brazil from a predominantly rural to a predominantly urban country. 2 Another migra-