Passport rules for traveling to the Caribbean, Canada and Mexico changed once again on Sept. 29 by action of Congress.

Under the new rules, all travelers entering the United States by air from these areas must present a passport starting Jan. 8.

The new deadline for people entering by land or sea from these areas is June 1, 2009. Such travelers, unlike fliers, will be able to present either a passport or a new document called a PASS card that has yet to be issued, said Steve Royster, spokesman for the Bureau of Consular Affairs at the U.S. State Department.

The bottom line: "If you want to fly, now is the time to apply for a passport," Royster said, adding that it can take four to six weeks to receive one. For details, call (877) 487-2778, or visit www.travel.state.gov.

Cruise and car travelers can wait longer to apply for a passport, if they wish, although some experts said they should get one soon.

"It's so much easier to have a passport," rather than carry several ID documents, said Cheryl Hudak, president of the American Society of Travel Agents. You'll also be covered for the unexpected, such as having to fly home in an emergency, she added.

Deadlines for the new border rules have shifted several times. Until Sept. 29, they had been Jan. 8 for both air and sea passengers and Jan. 1, 2008, for land travelers.

After protests from the travel industry, which said stricter rules would discourage travel, Congress voted to extend the deadlines for sea and land crossings.

The new PASS card, which stands for People Access Security Services, is expected to cost less than $50, compared with $97 for an adult passport.