Mexico? Canada? Get Your Passport Out.
Back in 2004, Congress approved the Western Hemisphere Travel Initiative. It dictated that in order to cross the border back into the country from either of the United State's two neighbors, a passport would be required. Today, that law goes into effect.
Beginning today, Americans returning from Mexico and Canada must show valid passports, a sharp departure from previous regulations that let U.S. citizens use only a driver license as proof of residency. [...]
Now, any U.S. resident 19 and older will need to show border agents a passport, one of several forms of federal identification, or a combination of two documents, such as a driver license and a birth certificate, before entering the country by land or sea. [Daily News]
Image from the State Department