Air travelers entering the U.S. will be required to show passports beginning Jan. 23, including returning Americans. The requirement - intended to make it harder for terrorists with fake IDs to enter the U.S. -marks a change for Americans, Canadians, Bermudans and some Mexicans. Currently, U.S. citizens returning from other countries in the hemisphere are not required to present passports but must show other proof of identity such as driver's licenses or birth certificates. (Source: AP)