I have no clue why North Dakota originally set it up that way. According to this link (http://www.nd.gov/sos/electvote/voting/vote-history.html), there was a Senate bill to start voter registration, but was considered too costly for the state.

Voter identity is probably verified the same way it is for you. Some sort of government issued ID and/or a piece of mail showing at least 30 days residence. In 2000 I voted on a ND college campus and had no problems at all. In 2004 I missed voting by one hour. I'm hoping/assuming that it'll be the same thing this time around.