This article explores the circuits of migration among American prostitutes in Mexican border towns between the years 1910 and 1930. After California’s Progressive movement shut down the state’s red light districts, American prostitutes found that the vice districts of Mexicali and Tijuana offered opportunities for economic and social advancement not available to them in the United States. As transnational subjects, these U.S. women exploited the ethno-cultural complexities of the border to claim “whiteness” as “Americans” and yet also relied on the Mexican state to guarantee their rights and liberties. Their story contributes to scholarly debates about prostitution and speaks to the absence of research on American women in the historiography of the twentieth-century U.S.-Mexican border.