Arturo Ramirez has crossed the border as an undocumented migrant every few years to work in the Florida orange groves. He says that stricter border enforcement implemented after September 11 made entering the United States far more dangerous and costly. But despite the increased risks, Ramirez headed for the United States.

Each year, Francisco Morelos leaves the small community in Mexico’s Querétaro state, and enters the United States to seek work. Many like him dream of starting their own business and do so by laboring in the United States as undocumented workers and sending their earnings back home.

We live a world of borders and walls. Invariably, the barriers are justified in the language of security—the country must be protected from the terrorists, drug cartels, insurgents, or suicide bombers lurking on the other side. Despite the external focus of these justifications, in most instances these walls and fences are actually the result of the internal politics of the state that builds them.