ALLEGHA'NY

, The chief ridge of the great chains of mountains which run from N. East to S. West through the middle and southern states of North America; but, more appropriately, the main or unbroken ridge, which casts all the waters on one side to the east, and on the other side to the west. This ridge runs from Pennsylvania to Georgia, and chains extend through the United States.

This name is given also to the river Ohio, above its confluence with the Monongahela; but improperly, as the Indian name of the river to its source is Ohio.