This essay examines the history of the taco in Mexico and the United States as a way of shifting the focus of "McDonaldization" from technology to ethnicity. It begins with the origins of the taco in Mexico to show that it was a product of modernity rather than an ancient tradition transformed by Yankee ingenuity. It then examines patent records, cookbooks, and archival sources to demonstrate that all aspects of the Mexican American taco, including the pre-fried taco shell, were actually invented within the ethnic community. Indeed, new forms of tacos were one of the many ways in which ethnic women mediated the boundaries between Mexican family traditions and U.S. cultural citizenship. These sources also refute corporate hagiography attributing the fast food taco to Glen Bell, founder of Taco Bell. Finally, using GIS to map taco shops against tract-level census data, the essay concludes that non-ethnic fast food chains succeeded by marketing tacos as a form of exoticism or safe danger within the segregated landscape of 1950s Los Angeles.