My thought exactly. If you took out the borders, many states would still be visible. I would expect the boundary between Tennessee and Kentucky, for example,

My thought exactly. If you took out the borders, many states would still be visible. I would expect the boundary between Tennessee and Kentucky, for example, to be more-or-less invisible, as between Texas and Arkansas. But even Oklahoma is distinguishable from northern Texas, despite basically no cultural or political difference across the Red River.