Effective June 1, 2009, all travelers entering the United States or Canada, by land or sea, will need to be in possession of a valid document. In most cases, this would be a U.S. or Canadian passport. There are also “trusted traveler cards,” “U.S. passport cards,” and, in some instances, “enhanced driver’s licenses” which will serve the same purpose. People trying to travel between the U.S. and Canada who are not in possession of one of these documents will be refused entry.