When a US president wants to play sheriff for a news cycle or two, immigration policy tends to be the obvious arena in which to do it. The migrant interdiction regimes established by recent presidential administrations, Republican and Democrat alike, have all served to intensify US-bound migrants’ special vulnerability to exploitation, interception, detention, and death. But each president has accomplished this awful objective through his own preferred mechanisms of control, the rippling effects of which inevitably extend far beyond the US-Mexico border, distorting social relations and entangling millions of lives throughout the hemisphere and indeed the world.

Bill Clinton, for example, sought to harden the border through a series of cartoonishly named special security operations — “Operation Gatekeeper” in California; “Operation Hold the Line” in Texas; “Operation Safeguard” in Arizona — that transformed the spatial trajectory of the migrant trail by pushing migrants into some of the most dangerous landscapes on Earth. George W. Bush established the loathed Immigration and Customs Enforcement (ICE) to ensure that the migrant trail would no longer have any dependable end point — even those migrants who managed to reach the United States could expect to be hunted for life.

Famously, Barack Obama strode into office pledging to fix a “broken” immigration system. Responding in large part to the wave of unaccompanied children arriving at the US-Mexico border from Central America, Obama quietly initiated his Programa Frontera Sur, or Southern Border Program, in 2014. Although secretive at the time, Obama’s gambit is now well understood: with the Southern Border Program, the Obama administration effectively outsourced US immigration enforcement to Mexican authorities, who, flush with American cash and armaments, committed themselves to searching out and expelling northbound migrants — especially children — before they could ever reach the US border and exercise their right to request asylum.