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Blue Mountain (Pennsylvania) facts for kids

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Blue Mountain
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)
Blue Mountain Ridge (Pennsylvania).jpg
The "Great Wall" of Blue Mountain
Highest point
Peak Clarks Knob 2,320 feet (710 m)
Elevation 1,129 ft (344 m)
Length 150 mi (240 km) northeast-southwest to SSW 150 miles (240 km) (direct aerial)
255 miles (410 km) trace of ridgeline, including loops back
width = varies along chain's length
Country United States
Orogeny Appalachian Mountains
Age of rock Silurian
Type of rock Tuscarora Formation and Shawangunk Formation; sedimentary
Physiographic provinces of Pennsylvania, Pennsylvania Geological Survey, 4th ser., Map 13, Pennsylvania Geological Survey of the PennDepCons&NatRes
Physical Geography schematic of Pennsylvania rock records. Notice the dramatic curve of the Allegheny Front.

Blue Mountain, Blue Mountain Ridge, or the Blue Mountains of Pennsylvania is a ridge of the Appalachian Mountains in the Lehigh Valley region of eastern Pennsylvania. Forming the southern and eastern edge of the Ridge-and-Valley Appalachians physiographic province in Pennsylvania, Blue Mountain extends 150 miles (240 km) from the Delaware Water Gap on the New Jersey border in the east to Big Gap in Franklin County, south-central Pennsylvania, at its southwestern end.

Views of Blue Mountain dominate 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 pass through either large water gaps (west to east: the Susquehanna, Schuylkill, Lehigh and Delaware River valleys) or wind gaps, low gaps in the ridge caused by ancient watercourses. The barrier ridge forms a distinct boundary between a number of Pennsylvania's geographical and cultural regions.

To the south of the Susquehanna River gap in the south-central part of the state is the Cumberland Valley, part of the Great Appalachian Valley; 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 the Coal Region of northeast Pennsylvania, the Wyoming Valley, and the distant Poconos. To the south of Blue Mountain lies the "Capital Region" of Harrisburg and nearby communities, the rich farming country of the Lebanon Valley and the Pennsylvania Dutch Country of York and Lancaster counties, the lower half of the Lehigh Valley, and the lower Delaware Valley; the latter two extend north 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.

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

Water gaps

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

The Pennsylvania Turnpike

Blue Mountain Tunnel portal
The western portal of the eastbound Blue Mountain Tunnel.

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

  • The Blue Mountain Tunnel carries the Turnpike's east-west mainline (Interstate 76) through the ridge in northern Franklin County. The Kittatinny Mountain Tunnel bores through a parallel ridge of the same mountain just to the west, with the two tunnel portals only 0.2 miles (0.32 km) apart.
  • The Lehigh Tunnel, so named to avoid confusion with the former, carries the Turnpike's north-south Northeast Extension (Interstate 476) through the ridge between Lehigh and Carbon Counties.

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

Blue Mountain attractions in Pennsylvania

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

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