The Mexican Migration Project began with a simple question: which Mexicans go where in the United States? It seems a simple and obvious inquiry, but it is mostly ignored in the U.S. public discourse. The tremendous heterogeneity of Mexico and the Mexicans, so evident on the ground, is subsumed in analysis that either categorizes all Mexicans as essentially the same — or worse, groups them together with other national-origin groups under the rubric of “Hispanic,” “Latino,” et cetera.

The erasure of meaningful differentiation by means of broad categorization has the effect of obscuring understanding and skewing analysis. The civic, cultural, religious, and political habits of a person with roots in the rural Chiapas highlands will of necessity be quite different from those of a person raised under the glass towers of Monterrey. Their differences will probably be ones of ancestry, ethnicity, history, and perhaps even language. There is a Mexican nation — but like the American nation, within it are many peoples.

Understanding this plausibly means understanding how they engage in the civic space and public square once in the United States. Take, for example, the political differentiation between Mexican-Americans in Texas, and those in California. The former group has famously been moving rightward in the past few election cycles. (This can be overstated: that rightward movement tracks notably well with the old Nuevo-Santander colonization, and less well with the San-Antonio and New-Mexican colonizations, of which El Paso is Texas’ possession within the second.) The latter group has not exhibited the same meaningful political movement. Why not?

The Mexican Migration Project suggests some answers. Look at the origins of Mexicans in Texas: they are concentrated in Tamaulipas, San Luis Potosí, and Guanajuato. By contrast, the Mexicans in California come disproportionally from a southern-coastal belt extending from Jalisco to Oaxaca. (When you look at the U.S.-wide map, the California pattern turns out to be the norm, and the Texas origins the exception.) These are significantly different parts of Mexico, and therein may be keys to differing outcomes within the United States.

This is an important point to be made about the Mexican Migration Project: it is a first step. Having established which U.S. state has which Mexicans, we are acutely conscious that the what does not definitively establish the why. In seeking answers here, we come away with more questions. That’s how good research is supposed to work. With Mexican-Americans at the forefront of the Hispanic populations transforming American life in myriad ways, the Mexican Migration Project offers a new and exciting starting point for understanding that transformation — and its origins.