My definition is basically hydrological. I'd define it as the portion of the United States draining to the Great Lakes (with the possible exception of the Lake Ontario drainage basin), all of the Ohio River valley north of the Ohio or east of the Guyandotte, all of the Mississippi valley north of the Ohio, and all of the American portion of the Missouri valley contained in the Central Time Zone, along with the portions of Minnesota and the Dakotas within the Central Time Zone that are not otherwise included in this definition.
Green: Entirely included
Blue: Partially included
Red: Very small portion included
Poll
