Verified answer

You do not need a passport if you are re-entering the United States by land or sea until June 1st, 2009. You do need proof of citizenship, an official copy of your birth certificate and a state issued photo ID will suffice.

You do need a passport if you are entering Canada and returning to the United States by air.

Note that it is not Canada's requirement that you have a passport to enter Canada, but that you must have one to re-enter the United States, even if you are a citizen.

Yes, you need a passport. I went to Toronto a few years ago and montreal a year ago, definitely get a passport. Also, the biodome is awesome and so are the gardens. =0). Also, if your 18 The Vatican (it's a club) friggin rocked.