Mexican Waves offers a clearly written and carefully researched investigation of radio broadcasting's role in shaping the United States–Mexico borderlands into a binational cultural zone during the period 1930–50. Well before railways or roads connected the region and even before Baja California became a state, commercial stations covered the vast northern border of Mexico and helped build economic and cultural connections to the southwestern United States. Robles draws on diverse archival and published sources, the most important of which are the records of over 100 radio stations in the Ministry of Communications and Public Works (SCOP) collection at the Mexican national archives. Robles uses these documents to explore the ways that federal officials and distant radio stations negotiated border broadcasting practices. She argues that although federal regulators attempted to enforce national norms, they ultimately adapted legislation and regulatory practices to the distinctly “transnational vision” of border stations (p. 142). Mexican Waves offers an original analysis of these border stations' operations that makes an important contribution to Mexican radio studies and borderlands history.Robles estimates that over one million Mexicans immigrated to the United States following the Mexican Revolution of 1910, drawn by the economic pull of Los Angeles and, to a lesser extent, San Antonio, San Diego, and El Paso. In response to this migration, 75 new commercial stations opened in Mexico's six border states between 1932 and 1950. Robles extrapolates that these stations “had a direct role in shaping Mexican immigrant communities, their consumption practices, and the growth of their small businesses in the United States” (p. 12). This is not a study of immigrant communities, so this claim invites further investigation. However, Robles provides evidence that the border stations primarily targeted Spanish-speaking immigrants in the Southwest.Chapter 1 examines how the Mexican government and entrepreneurs turned to radio to connect with Mexicans living in the United States beginning in the 1920s. By the 1930s the government was collaborating with commercial stations to use programs such as La Hora Nacional (The National Hour) to remind immigrants of their ties to the homeland. With only a few US stations broadcasting in Spanish for one to two hours daily, immigrant communities were an underserved market (p. 44). Chapters 1 and 4 would benefit from more analysis of the Depression-era deportation of people of Mexican descent from the United States and its impact on border radio. It is important to know how this process specifically affected border towns, their radio stations, and the style and substance of border broadcasting.Chapter 2 details the Mexican government's complex and contradictory relationship with border stations during the 1930s, particularly its use of radio to battle the “encroaching influence of the United States in Mexico” (p. 86). By the mid-1930s SCOP required all stations to hire Mexican citizens, broadcast in Spanish, and provide four hours daily of “pro Mexico” content if they operated a high-power transmitter (p. 51). At the same time, SCOP looked favorably on efforts to promote US tourism to Mexico, which typically required English-language programming aimed at US citizens. Chapter 3 explores the activities of local interventores (auditors) paid by SCOP to monitor those stations, and chapter 4 situates radio in relation to other forms of cultural circulation in the borderlands, including theater and music.Chapter 5 looks more closely at the records of 20 stations in order to track important changes in the 1940s and identify three different audiences targeted by border stations: Mexican immigrants in the United States, listeners in Mexican border towns, and English-language listeners in the United States. The market position of border stations improved during World War II when the US government prohibited broadcasting in Spanish. Around the same time, SCOP established a “tax on advertisements from the United States,” which both signaled acceptance of border stations' transnational business model and created an avenue for the government to benefit from that model (p. 129).Drawing on original archival research, Mexican Waves provides an alternative to the prevailing view of English-language “border blasters” detailed by Gene Fowler and Bill Crawford in their well-researched but anecdotal history. While they focus on the impact of a few high-power stations on US music and culture, Mexican Waves looks at border radio as an aggregate of mostly smaller stations engaged in “multifaceted marketing campaigns” targeting primarily Mexican immigrant audiences (pp. 137–38). Robles's study captures a unique moment in border history before the influence of small-time stations was challenged by both US Spanish-language radio and Mexico City–based commercial networks.