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Blue Mountain Ridge, Blue Mountain, or the Blue Mountains of Pennsylvania is part of the geophysical makeup of the Ridge-and-Valley Appalachians in the U.S. state of Pennsylvania. It is a ridge that forms the southern and eastern edge of the Appalachian mountain range spanning over 255 miles (410 km) from the Delaware Water Gap as it cuts across the eastern half of the state on a slight diagonal from New Jersey tending southerly until it turns southerly curving into Maryland, and beyond.

Blue Mountain[2]
Kittatinny Mountain (and nine others:
 • Blue Hills,  • Kau-ta-tin-chunk,  • Kekaghtenemin Mountain
 • Kightotinning Mountain,  • Kittachtinny Hills,
 • Kittatinhy Mountain,  • Kittochtinny Hills,
 • Kittochtinny Mountains,  • North Mountain)[2][3]
Blue Mountain.jpg
The "Great Wall" of Blue Mountain
Highest point
PeakClarks Knob 2,320 feet (710 m)[4]
Elevation1,129 ft (344 m) [2]
Coordinates40°07′28″N 77°39′59″W / 40.12444°N 77.66639°W / 40.12444; -77.66639Coordinates: 40°07′28″N 77°39′59″W / 40.12444°N 77.66639°W / 40.12444; -77.66639
Length150 mi (240 km) northeast-southwest to SSW 150 miles (240 km) (direct aerial)
255 miles (410 km) trace of ridgeline, including loops back[5]
width = varies along chain's length
CountryUnited States
Borders onRidge-and-Valley Appalachians and Great Appalachian Valley
OrogenyAppalachian Mountains
Age of rockSilurian
Type of rockTuscarora Formation and Shawangunk Formation; sedimentary
Physical Geography schematic of Pennsylvania rock records. Notice the dramatic curve of the Allegheny Front.

Some distant view of The Blue Mountain dominates the southern tier of most eastern and central Pennsylvanian counties providing an ever visible backdrop cutting across the northern or western horizon. Most transport corridors and road beds piercing the barrier necessarily descend through either large water gaps (West to east: Susquehanna, Schuylkill, Lehigh and Delaware River valleys) or wind gaps their smaller tributary gaps cut by creeks, brooks, and lesser rivers. The descent into the southern lowlands are ramplike and before southbound travelers oft lays a scenic panorama spread from horizon to horizon. The barrier ridge forms a distinct boundary between a number of Pennsylvania's geographical and cultural regions.

To the north of the Susquehanna Gap in the south-central part of the state are the Cumberland Valley tucked in the area above the water gap as if trying to flow through with the river; to its northwest side are the southern reaches of the Susquehanna Valley with picturesque streams channeling travel corridors deep into and over the central and western mountains and valleys—the heartland interior counties of Pennsylvania; along the Main Branch Susquehanna, the valleys also lead into northeast Pennsylvania, into the "Northern Coal Region", of the Wyoming Valley and the distant Poconos. To the Blue Mountain Ridge's center, on the southern side lies the "capital region", about Harrisburg and nearby communities, the rich farming country of the Lebanon Valley, and Pennsylvania Dutch Country of York and Lancaster Counties, the lower half of the Lehigh Valley and the lower Delaware Valley; the latter two extend through water gaps beyond the ridgeline.


The ridge of Blue Mountain runs for 150 miles (240 km) through Pennsylvania, reaching an elevation of 2,270 feet (690 m) above sea level just north of the Pennsylvania Turnpike, near the borough of Newburg. Most of the ridgecrest, however, only reaches between 1,400 feet (430 m) and 1,700 feet (520 m) in elevation. The mountain's width varies from 1 mile (1.6 km) to 3 miles (4.8 km).

The southwestern end of the mountain is at Big Gap, west of Shippensburg. (The mountain ridge continues to the southwest towards Maryland under the name of Broad Mountain.) The northeastern end of the mountain is at the Delaware Water Gap on the New Jersey border. Mount Minsi forms the promontory overlooking the Delaware River. The ridge of Blue Mountain continues northeast into New Jersey as Kittatinny Mountain.[6]

Blue Mountain marks the boundary between the Great Appalachian Valley and the main Ridge-and-valley Appalachians.

Water gapsEdit

Four of Pennsylvania's major rivers cut through Blue Mountain in water gaps.

The Pennsylvania TurnpikeEdit

The western portal of the eastbound Blue Mountain Tunnel.

The Pennsylvania Turnpike system passes through the Blue Mountain at two points.

Both tunnels (each consisting of two tubes) carry two lanes in each direction of travel.

Blue Mountain attractions in PennsylvaniaEdit

Blue Mountain School District is named after the mountain range. It is located just off Rt. 61 in Schuylkill Haven, Pennsylvania.

See alsoEdit


  1. ^ "Blue Ridge Mountain". Geographic Names Information System. United States Geological Survey. Retrieved 2017-03-29.
  2. ^ a b c "Blue Mountain". Geographic Names Information System. United States Geological Survey. Retrieved 2009-02-07.
  3. ^ What's in a name, Spanning the Gap newsletter of the Delaware Water Gap National Recreation Area, Summer 1984
  4. ^ "Clarks Knob". Geographic Names Information System. United States Geological Survey. Retrieved 2009-02-08.
  5. ^ Measured along ridge point by point using ruler tool, anchored on New Jersey border, to Maryland border., 29 March 2017.
  6. ^ U.S. Geological Survey 1:24,000-scale and 1:250,000-scale topographic map series

External linksEdit