WASHINGTON — Shelley Jackson was 7 years old the first time she heard it.

In the early 1970s, Ms. Jackson was among a group of 40 black children who were bused from one side of Los Angeles to integrate a majority-white school across town. One day, a playground squabble ended in a white classmate telling her to go back to Africa.

“That day was the first day that I became aware that maybe we weren’t supposed to be there,” Ms. Jackson, who was born in California, said in an interview, “or that wasn’t our place.”

On Sunday, President Trump used a version of a well-worn insult to tell four congresswomen to “go back and help fix the totally broken and crime infested places from which they came. Then come back and show us how it is done.” All but one are American-born, but all are women of color.

The president’s words reflected a love-it-or-leave-it sentiment that experts say has animated a sense of xenophobia since the dawn of the republic.