Does anyone if you travel to Canada if you need a passport or not?

I want to go back to Canada, I haven't been there in awhile I was told that you need to carry a passport. Is this true.

Yes, sadly, it is true now.

Yes.

The above two answerers are wrong. I live in Windsor, Ontario and cross the Ontario-Michigan border all the time. Assuming you are American, and are talking about LAND travel (not flying) at present you require the following: (1) valid government-issued photo ID, such as your driver's licence, and (2) your original birth certificate. The passport issue has been delayed until at least June, 2009, as they are looking at the option of going with an enhanced driver's licence, so for now, you will be fine with the above.
Have fun!

if you are an American citizen you need a passport only if your flying to Canada

if driving you need government issued photo ID and a birth certificate

all this will change in June 2009 you will need a passport to enter Canada and to return to the US