Suddenly thousands of people were traversing the state and because this diversion coincided with the construction boom in Phoenix, many settled there to take jobs. Mr. Massey notes that the crossing of thousands of Mexicans between Tijuana and San Diego or Juarez and El Paso is not particularly visible given that both areas have millions of people and the US-side cities are heavily Mexican to begin with.
“But tens of thousands of Mexicans showing up in Douglas, Arizona and crossing open ranch land make a big impression,” he says, “making illegal migration much more visible and of course quite disruptive to local ranchers.”
Yet Arizona's current immigration drama may not owe its entire existence to history or demographics. Republican politics play a role too, says Aarti Kohli, Director of Immigration Policy at the Chief Justice Earl Warren Institute on Race, Ethnicity at UC Berkeley School of Law.