As to Delaware and Maryland, there may be a difference of opinion, though it is difficult to justify the inclusion of the former.
West Virginia is certainly not Southern, socially, politically, or economically.

Kentucky is doubtful, and it is difficult to see why Missouri should be excluded from any list which includes Kentucky.
Oklahoma is difficult to classify.

But, at any rate the South is a large country, with a great variety of soil, climate, and population.

As the crow flies, the distance from Richmond to Memphis, in an adjoining State, is greater than from Richmond to Bangor, Maine.

From Richmond to Galveston is farther than from Richmond to Omaha or Duluth.