In a world where people are more mobile than ever, nations are struggling to recalibrate who can be a citizen.

More than 30 countries grant unrestricted birthright citizenship based on the ‘jus soli’ principle – and nearly all of them are in the Western Hemisphere. The reason is more complicated than you might think.

Unrestricted birthright citizenship is increasingly rare, and with only a few exceptions, it persists only in countries with negative or near-zero rates of

President Trump’s order curtailing birthright citizenship faces lawsuits over the 14th Amendment. This may be prelude to other efforts to end it.