<p>You do need a passport now if traveling by air, but not by car. (I’m not sure what the rule is if traveling by water.) In January 2008, a passport is required no matter how one travels.</p>
<p>There may be a possible exception of frequent visitors from U.S. to Canada. I know that Maine’s Senators have been working on this, as it’s important for trade between Canada and Maine and for folks who live on the border and have relatives and friends on both sides.</p>