Very briefly, the announcement has been made that by 2008 or so it will be impossible for Americans to reenter from Canada, Mexico, Bernuda, etc. without having a passport.
Most Americans do not have passports, and spending a significant sum of money and go to fair inconvenience to drop across the Niagara River to have dinner in Niagara-on-the-Lake may not be readily convincing as a readon to get one.
Thus, the Canadian tourism will fade, as will the on-border Mexican sites.
Bush, a true genius.