480 THE POPULAR SCIENCE MONTHLY 



normally terminated. The distribution of the Pennsylvanian forma- 

 tions coincides with the most irregular topography of the state. The 

 average altitude is about 770 feet, and the range in altitude is approxi- 

 mately 1,100 feet. 



The present watershed crosses the state from east to west, trending 

 slightly to the south, at an altitude of about 1,100 feet. Drainage 

 lines have divided the upland portion into north-south trending blocks 

 progressively more widely spaced towards the west. These low tracts 

 have been used by the canals and railroads connecting Lake Erie and 

 Ohio Eiver. 



The larger part of Ohio is an almost completely severed portion of 

 the Allegheny plateau, extending westward from the northwestern part 

 of Pennsylvania like a great spit into the Mississippi lowlands; the 

 broad valley of the Ohio resembles a bay between this spit and the 

 western slopes of the Appalachians. This somewhat peculiar relation- 

 ship of topography is the combined result of drainage adjustments due 

 to stratigraphy, and slight diastrophic movements. 



Using natural boundary lines, it would be difficult to divide North 

 America into many states. Where such lines do exist, they have not 

 always been utilized. Lake and river, however, form over half the 

 border of Ohio. In general, a water boundary is an asset to a com- 

 monwealth; it may be a protection from disputes, and a transit to 

 trade. The reaction varies with other natural boundaries: high alti- 

 tudes, sometimes barriers, may impose aloofness, or almost complete 

 isolation, whereas water boundaries invite commercial relations. 



Geographically Ohio is the back door of the middle and north At- 

 lantic states. This relationship has been of reciprocal value to both 

 areas; as population became more and more dense in the early settle- 

 ments, and knowledge of the broad lands across the Appalachians spread, 

 a movement in that direction was natural. The easiest route for the 

 more northern of the Atlantic states was through New York via the 

 Mohawk valley, out and along Lake Erie ; for the more southern states, 

 through passes in the mountains. Possibly on account of the narrow 

 coastal lands to the south, or possibly because of the greater enterprise 

 there in watching the movements of the French, the southern routes 

 were first explored, and the earliest movements into the Ohio valley 

 came either by way of Pittsburg or by the course of the Cumberland 

 road. 



A gross classification of the factors in the development of any re- 

 gion is (1) internal and (2) external. The external include the 

 boundary itself in case the region is a natural one; but geographic 

 situation is frequently very important. When avenues of travel and 

 traffic converge and pass through a state benefit follows. Advantage 

 always comes from proximity to great centers of business or culture 



