In order to qualify to be president, the U.S. Constitution states, "No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States."

So what defines a "natural-born citizen"?  The answer has not been so simple over the years.