"The pace of growth accelerated further in January 2007 when U.S. citizens traveling by air between the U.S. and Canada, Mexico, Central and South America, the

"The pace of growth accelerated further in January 2007 when U.S. citizens traveling by air between the U.S. and Canada, Mexico, Central and South America, the Caribbean, and Bermuda were required to have a valid passport. Previously, it was possible for them to enter those countries without one" https://www.forbes.com/sites/niallmccarthy/2018/01/11/the-share-of-americans-holding-a-passport-has-increased-dramatically-in-recent-years-infographic/ https://www.forbes.com/sites/niallmccarthy/2018/01/11/the-sh...