The pattern you circle along the 'Ohio River' correlates in (the north) with
Cleveland and Pittsburgh, both traditional blue-collar union towns.

Actually, none of the blue areas correspond with the Ohio river except around Pittsburgh. The blue areas south of the Mason/Dixon line i don't know about. They're not along the Ohio River, though. The blue pattern does look, vaguely, like it follows the ridge lines of the western Appalachians, so there may still be a link between geography and voting here. I'd have to pull up a terrain map to be sure.

What I find interesting are states like Ohio, for which the eastern half was generally for Gore or Bush only carried a plurality, while the western half was solidly in Bush's camp -- you can draw a straight north-south line through the state. Cities like Cincinnati and Columbus appear to be entirely sold over to Bush, which puts a spin on the usual urban/rural split.