When I flew home for Christmas, they were flashing this message on the televisions before the movie started: Anywhere outside the US and you need a passport, and that includes Canada and Mexico.

I applied for my passport and they said they weren't very busy, it'd probably take 2 weeks, call them if I hadn't gotten it in 8 weeks. IT WAS A FULL 8 WEEKS BEFORE I GOT IT. So just be on the safe side. There was an option to have it overnighted to you once it was completed, you just paid the $14 for the overnight envelope, not the $60 for expediting the whole process. That's supposed to shave a few days to a week off the process.

Direct from the U.S. Department of State
 

Under the Western Hemisphere Travel Initiative (WHTI)
The proposed implementation timeline has two phases:

• Beginning January 23, 2007, ALL persons, including U.S. citizens, traveling by air between the United States and Canada, Mexico, Central and South America, the Caribbean, and Bermuda will be required to present a valid passport, Air NEXUS card, or U.S. Coast Guard Merchant Mariner Document, or an Alien Registration Card, Form I-551, if applicable.
• As early as January 1, 2008, ALL persons, including U.S. citizens, traveling between the U.S. and Canada, Mexico, Central and South America, the Caribbean, and Bermuda by land or sea (including ferries), may be required to present a valid passport or other documents as determined by the Department of Homeland Security. While recent legislative changes permit a later deadline, the Departments of State and Homeland Security are working to meet all requirements as soon as possible. Ample advance notice will be provided to enable the public to obtain passports or passport cards for land/sea entries.

The passport requirement does NOT apply to U.S. citizens traveling to or returning directly from a U.S. territory. U.S. citizens returning directly from a U.S. territory are not considered to have left the United States and do not need to present a passport. U.S. territories include the following: Guam, Puerto Rico, the U.S. Virgin Islands, American Samoa, Swains Island, and the Commonwealth of the Northern Mariana Islands.


To be safe, I would get an expedited Passport if I were you, especially if this is a new passport and not just a renewal. OH, and don't go to a private passport "agency" to get it...there are all kinds of fraudsters out there right now ripping people off in passport schemes, and even the legit ones don't do anything but slow the process down and charge you even more money for it.

ETA: whenever you want to know the answers to travel questions like this, it's best to go directly to the state department's Web site. There's actually a TON of very useful information on it. I always go there to check on any foreign travel advisories, too.

In November when I traveled to I traveled to Italy, I didn't have passport, I applied for an rush passport between 11/1 and I received my passport on 11/8.

I was going to go through a service because I didn't have a copy of my full birth record, I went down to th department of records, got it same day; the next day I went to the post office and did express mail.

If you need one, expedite it. Before this new requirement, it wasn't a big deal to apply and get your passport 2-3 weeks later. My sister needed a passport for our trip to Europe and she applied maybe 9 weeks before it. After 4, she called the State Department, and they said that they were seriously backed up because of the new requirement. Luckily, they were able to expedite it while it was in process. They Fed Ex-ed it to her house the day before our trip--9 weeks after applying.

This is all a moot point if you're in a big city where you can go to a Passport Agency.