Starting January 31st, 2008 and until January 2009, US borders will require you to show I.D. with a picture issued by a state agency (driver's license for example) AND a birth certificate.

 

 A passport can replace these 2 documents.

 

A birth certificate is enough for less than 18 years old.

 

The obligation of having a passport to cross overland borders has been postponed to the beginning of 2009.

 

A passport is reguired since january 2007 if you travel by plane.