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.

The policy was the result of African Americans pushing for decades to be recognized as full citizens and part of a trio of amendments — the 13th, 14th and 15th — that ended U.S. slavery and established citizenship and voting rights for some people of color.