President Donald Trump has falsely claimed the U.S. is alone in offering citizenship as a birthright. More than 30 countries do — but some have rolled it back.

President Trump's bid to cut off birthright citizenship is "flagrantly unlawful," attorneys for 18 states said in a lawsuit challenging the president's executive order.

After the Civil War, the Constitution was amended to consider every baby born in the US an American. Soon that may change.