1911 Encyclopædia Britannica/Alleghany
ALLEGHANY, or THE ALLEGHANIES (a spelling now more common than Allegheny), a name formerly used of all the Appalachian Mountains (q.v.), U.S.A., and now sometimes of all that system lying W. and S. of the Hudson river, being steep and narrow-crested in Pennsylvania (1500–1800 ft.), and in Maryland, Virginia and West Virginia higher (3000 ft.–4473 ft). and with broader crests. Another usage applies to the ridges (“the Allegheny Ridges”) parallel to the Blue Ridge; the north-western part of this region is sometimes called the Allegheny Front or the Front of the Allegheny Plateau. The Allegheny Plateau is the north-westernmost division of the Appalachian system; it is an eroded mass of sedimentary rock sloping north-westward to the Prairie and Lake Plains and reaching south-west from the south-western part of New York state through Tennessee and into Alabama.