I've crossed at Detroit/Windsor many times, and have never had a problem getting into Windsor. They've always asked for some sort of ID (even before 9/11), and while it's true that legally speaking, you need: 1) a passport; or 2) photo ID plus proof of citizenship (e.g., birth certificate), they often just ask for photo ID.

Still, you want to have all necessary papers in order, just in case. Also, ask your auto insurance agent for a yellow Canadian insurance ID card, which verifies that your insurance is valid in Canada and meets all of their requirements. Canadian Customs has never asked me for it, but you'll want to have it if you get into an auto accident.

Other than wanting ID, Canadian Customs has always been nice and has never hassled me in any manner. I guess they want me to spend my American dollars there.

Getting back into Detroit is sometimes easier and sometimes harder. Even after 9/11, I've sometimes been let in without a request for any ID whatsoever. Other times, I've been singled out for a search. Sometimes they're friendly, sometimes they're rude, and sometimes they're merely polite.

BTW, for those of you unfamiliar with the Detroit/Windsor tunnel, the US end is located in downtown Detroit. I was amazed when, after 9/11, they pulled me aside and had several Customs officers interrogate me about importing Tylenol #1 (which is OTC in Canada). A terrorist could have crossed the border and brought something like a "dirty bomb" right into the middle of downtown Detroit because Customs was too busy hassling harmless me.