A FASCINATING picture of the Mexican-US borderlands is emerging and coming into ever clearer focus in a range of disciplines across the social sciences. River of Hope adds to this growing body of literature with an absorbing examination of identity formation in the lower Rio Grande region during the eighteenth and nineteenth centuries, a period in which competing powers – Mexico, the US and Spain – vied for control of the borderlands inaugurating a long history of changing and unequal relations. Valerio-Jiménez explores how in the febrile, often violent atmosphere of competition, the diverse residents of this region did not adopt singular and clear-cut colonial or national identities but that these were more likely to be shaped by regionalism, transnational cultural practices and kinship ties. Indian slaves joined Spanish society, Mexicans allied with Indians to defend their communities and Anglo Americans and Mexicans intermarried and collaborated. River of Hope reveals the sheer contingency of the national idea and how state formation was a fluid and often incomplete process without a beginning or an end, in some ways a feature of this landscape that remains as fixed today as it was then.