Canadians now need passports to cross, I would assume you could get across with one too. The US border gaurds look at you like you are crazy when you are on a bike, but I havent had any trouble getting in. Do it, things are different! No point in being so close and not seeing it. I do agree with Alfster, but live and learn. US government web site would tell you for sure what the deal is but quite sure that EU folks dont need any visas.