You are leaving too much unsaid. Where are you traveling from? What kind of 'document' are you talking about? Are there reasons to believe that travel will cause you some difficulty or inconvenience?
Used to be all you needed was your driver's license, but after 9/11 you might have a problem getting back to the U.S. side of the border without a passport. You can call 800-474-2252 and ask the...