President Trump has inspired widespread outrage and disgust with his crude, racist disparagement of Haiti, El Salvador and African nations and the predominantly black and brown immigrants from these places.

As horrifying as this remark was, his groundbreaking transparency provides an opportunity. Racism has long fueled United States immigration exclusions and restrictions, but these days it’s rare to hear rhetoric that openly reflects this reality, providing us a chance to delve into its roots and implications. ...

The nation’s first naturalization law, from 1790, closed off United States citizenship to all but “free white persons of good character.” People of African descent were among the first migrants singled out for surveillance and exclusion, as they sought entry to the country or moved between states. State repression of black migrants transformed them into America’s first “illegal immigrants,” laying the groundwork for durable associations between law, morality and the need to keep people of color, quite literally, in their “place.”

The racialization of United States immigration law took off in the decades following the Civil War. Beginning with the Chinese, migrants from Asia were the early targets; beginning in 1917, an “Asiatic Barred Zone” (with latitude and longitude markers laid out clearly in the legislative code) kept out migrants from an imaginary mega-region that stretched from contemporary Turkey to Papua New Guinea.

In the aftermath of World War I, a new “national origins” quota system sought to turn back the American demographic clock, with European immigrants admitted in proportion to the presence of their “nationality” in the American population based on earlier censuses. It was “Make America Great Again” for a eugenic age. Hitler was a fan. America appeared to be “a young, racially select people,” he wrote admiringly in 1928, by “making an immigrant’s ability to set foot on American soil dependent on specific racial requirements,” among other factors. ...