BBA,
Like I stated above... You will need a passport to get back into the US from Mexico starting December 06... In fact here is the thread about this topic... It even has the passport website where you can go and read for yourself... It's not getting into the countries that will a problem but getting back into the US without a passport will be a problem... I just went to the Bahamas in Feb. Called to book another cruise for November and was told go get your passport and it's true...