What do critics mean by “birth tourism,” “chain migration” and “anchor babies?”

Those terms, used by anti-immigration hard-liners and other critics of birthright citizenship, tend to conflate two separate consequences of the policy.

Each year, thousands of pregnant women from other countries enter the United States on a valid visa, give birth to children who automatically gain American citizenship, and then take the babies back home or to another country. The practice, sometimes called “birth tourism,” is legal as long as the mother obtains her visa truthfully and complies with its terms.

Mr. Trump and his supporters, however, tend to talk instead about expectant mothers entering the country illegally to give birth to what they derisively call “anchor babies” who would give the family access to public benefits and a foothold toward legal residence.

Undocumented immigrants have given birth to about four million children who are United States citizens, according to the Migration Policy Institute, a nonpartisan research outlet. But the overwhelming majority did not cross the border in utero. The Pew Research Center found that the parents of nine out of 10 of those children entered the United States at least two years before giving birth, suggesting that the parents migrated for other reasons.

Whether they are reared in the United States or abroad, American children of noncitizen parents who reach the age of 21 can sponsor family members for legal permanent residency, just as any other American citizen can — a practice derided by critics as “chain migration.” Sponsorship by relatives has featured prominently in the stories of tens of millions of immigrants to the United States over the last century.
The New York Times