The Western Hemisphere Travel Initiative (WHTI) – issued in 2006-07 – required that travelers show a valid passport when travelling to the U.S. A massive surge of citizens (30 million) got their passports then, but now, ten years later, these passports are expiring, and millions of new passports are expected to be issued in 2016-17. One a separate issue, travelers to Europe need to be aware that their passports need to be valid 3 months after their scheduled date of departure – as well with some Caribbean nations too.
Source: Travelmarketreport.com