“We're the only country in the world that has it. You step into our country and you're all of a sudden a citizen.”

Dozens of countries have it. The Law Library of Congress survey of the world's citizenship laws found 33 countries granting unconditional birthright citizenship, all but six of them in the Americas and the Caribbean, within a wider group of 94 countries that currently have, or recently had, laws granting citizenship by birth. Canada's Citizenship Act makes a citizen of any person born in Canada after February 14, 1977. Pew Research Center counted 32 other countries, most of them in the Western Hemisphere, with birthright citizenship laws substantially similar to the American one.

Something narrower is true, and it is the claim's best defence. Pew's finding is that American-style birthright citizenship is uncommon around the world, and at the same event he restated the claim in that narrower form, saying no other country does it the way this one does. Uncommon is not unique, and on the wider phrasing the claim is wrong by at least 32 countries.