Ohio is a political, not a geographic, unit. Its boundaries are imaginary; they exist only on paper. Many of the state's geographic features continue into its neighboring states and Canada. There are no high mountains or wide bodies of water, which completely separate Ohio from its neighbors. Lake Erie and the Ohio River are the only natural features that contribute to the state's political boundaries. Two of the original Colonies, Pennsylvania and Virginia, determined Ohio's eastern and southern boundaries when the Confederation Congress established the Northwest Territory. Later, the U.S. Congress fixed Ohio's western boundary, as well as its northern boundary west of Lake Erie when Ohio became a state. The international boundary with Canada through Lake Erie determined the rest of Ohio's northern boundary.
Still, Ohio has a distinct, overall geographic character. And it is important to understand the geography of Ohio in order to understand Ohio's history as well as it place in the world today.