Paperwork Needs??

I'm trying to find somewhere fun to take my husband for a romantic weekend away! Ok, so the Hockey Hall of Fame may not be that romantic...but he'll be really excited! My question is this, for travel between the U.S. and Canada do we need a passport? Or is it still just a drivers license? In Mexico you used to just have to say your country of origin, but now they require much more paperwork. I just don't know if Canada is the same way. If a passport is required, then I think it will be the Baseball Hall of Fame this year!!