Nobody in the thread said that North Dakota and South Dakota were one state. A Southern University fan, who admitted that he knew nothing about South Dakota (a big surprise to all you Louisiana experts out there, I'm sure), said that one of the Dakotas is located "just south of the Canadian border."
Based on the sentence structure, he could have been referring to either North Dakota or South Dakota. I'm guessing that he meant North Dakota because the north-south thing provides a rather obvious clue.