The U.S.-Mexico Border and the 1947 Foot-and-Mouth-Disease Outbreak in Mexico C. J. Alvarez (bio) The day after Christmas, 1946, a Mexican veterinary laboratory confirmed that cattle in the gulf coastal state of Veracruz were infected with foot-and-mouth disease, or fiebre aftosa in Spanish. Within days, the U.S. Bureau of Animal Industry, a division of the Department of Agriculture, shut down the entire U.S.-Mexico border to all animal traffic and animal products that could be contagious. Within two months, the U.S. Congress had passed a bill authorizing a bilateral commission to contain the outbreak. Over the next nine months, until late November, 1947, the Bureau of Animal Industry, alongside its Mexican counterpart, the Secretaría de Agricultura y Ganadería, embarked on a slaughter campaign in central Mexico to "stamp out" the disease.1 A year after the first outbreak, the commission had killed nearly 1 million animals, roughly half of which were cattle.2 This was the interior quarantine. As B. T. Simms, the chief of the Bureau of Animal Industry, put it, "we feel very strongly that it is better for us to fight the battle on Mexican territory than it is on our territory. The land boundary has never held foot-and-mouth disease. It either moves up or you move it back."3 After many people in the Mexican countryside resisted and protested against the deaths of their animals, the commission shifted to a vaccination program instead, but in both instances the quarantine line was guarded and enforced by the Mexican military. And despite Simms's preference for concentrating the violence in Mexico, the Bureau of Animal Industry also began patrolling the U.S.-Mexico border soon after the outbreak as a backup measure. This was the border quarantine. It was enforced by Customs inspectors at the official ports of entry, by armed officials of the Bureau of Animal Industry on horseback crisscrossing the vast open spaces of ranchland and desert between the ports, and by physical infrastructure, a [End Page 691] reinvigorated border fence building project. Over the course of three years, the Bureau of Animal Industry, in collaboration with the Immigration and Naturalization Service and the U.S. section of the International Boundary and Water Commission, worked together to complete 237 miles of fencing on the land border between the Pacific Ocean and the Rio Grande. This fence construction dwarfed all previous fence building projects; it was over five times longer than anything that had been built before along the international divide, and remained the most substantial border fencing construction until the Secure Fence Act barrier system of 2006. It was different than previous fence projects not only because of its length, but also because it was a collaborative project between both animal and immigration inspectors, and because it included a military component in Mexico, over 200 miles south of the border.4 I argue that this episode amounted to a signal transition in border history because it simultaneously reshaped the built environment of the western boundary and projected U.S. border controls deep into Mexico, thereby altering the geography of border policing that had previously been largely concentrated along the proverbial line in the sand. My analysis draws on several historiographic traditions, including histories of policing institutions, quarantines, agriculture, the Mexican military, and of the episode itself. By the time of the border closure, as several studies have shown, the development of federal law enforcement on the U.S. side had been underway for over a generation, and the U.S.-Mexico guest worker program (Bracero Program) between 1942 and 1964 had occasionally prompted Mexico to use its military to prevent unauthorized exit as millions of laborers traveled back and forth across the border.5 This scholarship focuses mainly on how the U.S.-Mexico border was politically, institutionally, and racially "constructed," but largely ignores the built environment of the international divide itself, as well as the nonhuman kinds of movement that helped structure U.S.-Mexico relations. The few studies that have examined the outbreak in terms of the border have either ignored or underestimated the scale and significance of the built...