Ten years ago the U.S. government began requiring citizens to carry a passport for travel to all countries, including Canada and Mexico. The State Department was blindsided by the increase in passport applications, and now all of those passports are due to expire. The renewal line is going to get mighty long, and there’s talk of increasing limitations on acceptable forms of identification. One last wrinkle: It’s increasingly common for countries to refuse entry to travelers with passports that expire in fewer than six months. Current wait time for passport renewals is six weeks, and it will go up.