a passport is very much recommended if you plan to travel abroad regularly (this includes e.g. one cruise per year or so). From December 31st, 2006 U.S. citizens will be required to have passports in order to travel within the Western Hemisphere by air or sea anyway, so I would suggest getting a passport now before everybody wants to get one.
Raoul is right. Already some Caribbean islands require a passport of non-cruise visitors from the U.S.(Barbados comes to mind.) And so far, Dec. 31, 2006 begins the requirement of having passports for Western Hemisphere travel.
Passports are a relative bargain; getting a new one may seem expensive, but considering it lasts 10 years, that's $10 or less per year!
I guess the best way to look at it ..If you ever plan to travel outside of the USA its time to breakdown ..beat the rush and get your passport. The sooner you apply the sooner you can quit worring "what do I need to travel!"
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