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Thegeography ofPennsylvania varies from sea level marineestuary to mountainous plateau. The state is known for its natural resources, ports, and the leading role it played in the founding and history of theUnited States.
Pennsylvania's nickname, the Keystone State, derives from the fact that the state forms a geographic bridge both between theNortheastern United States and theSouthern United States between theAtlantic seaboard andMidwest. The state's western toehold extends to theGreat Lakes atErie.
Pennsylvania is bordered on the north and northeast byNew York; on the east byNew Jersey; on the south byDelaware,Maryland, andWest Virginia; on the west byOhio; and on the northwest byLake Erie. It has a small border on Lake Erie withCanada. TheDelaware,Schuylkill,Susquehanna,Monongahela,Allegheny, andOhio rivers are the state's major rivers. TheLehigh River in the state's east andOil Creek in its west are smaller waterways that played vital roles in Pennsylvania's early industrial development. Pennsylvania is one of13 original colonies thatshare a border with Canada.
Pennsylvania is 180 miles (290 km) north to south and 310 miles (500 km) east to west. The total land area is 44,817 square miles (116,080 km2)—739,200 acres (2,991 km2) of which are bodies of water. It is the 33rd largest state in the United States. The state's highest point is 3,213 feet (979 m) abovesea level atMount Davis. Its lowest point is at sea level on the Delaware River.
ThePennsylvania Dutch region in south-central Pennsylvania is a favorite for sightseers. ThePennsylvania Dutch, including theAmish,Mennonites, and at least 15 other sects are common in the rural areas around the cities ofLancaster,York, andHarrisburg with smaller populations extending northeast to theLehigh Valley and up to theSusquehanna Valley. Some adherents eschewmodern conveniences and use of horse-drawn farming equipment and carriages, while others are virtually indistinguishable from non-Amish or Mennonites. Descendants of these plain sect immigrants, who do not practice the faith, often refer to themselves as Pennsylvania Germans.
Despite the name, the Pennsylvania Dutch are from various parts of southwestGermany,Alsace, andSwitzerland, not theNetherlands. The wordDutch is left over from the original meaning of the English word Dutch, which once referred to the entireWest Germanicdialect continuum.[1]
Western Pennsylvania, which comprises roughly a third of the state, is a separate large geophysical unit. Several factors set Western Pennsylvania apart from the east, including the initial difficulty of access across the mountains, rivers oriented to theMississippi River drainage system, and complex economics involved in the rise and decline of the Americansteel industry centered in and aroundPittsburgh, the state's second-largest city. Other factors, such as a markedly different style of agriculture, the rise of the oil industry, timber exploitation and the old wood chemical industry, andlocal dialect, all make Western Pennsylvania distinct from other regions of the state.
Pennsylvania is bisected in an S-curve, or roughly diagonally, by thebarrier ridges of theAppalachian Mountains from southwest to northeast, forcing pre-20th century ground travel most often on or near the ancient Amerindian trails along the higher terrains of the local watersheds with limited penetration and connectivity often only throughwater gaps. As rough looking as the first map appears, the valley bottoms throughout the entire central part of the state and parts of lowerNew York state are connected by theSusquehanna River and its tributaries, which included nearly the entire length of thePennsylvania Canal System in the 1830s. To the northwest of the folded mountains is theAllegheny Plateau, which lies above the cliff-likeAllegheny Front escarpment, continues into southwestern and south central New York, and is pierced in only a few places known as theGaps of the Allegheny.
TheAllegheny Plateau is dissected by valleys formed by small streams and springs with elevation differences between valley floors and hilltop peaks differences that usually vary by a few hundred feet. The plateau is underlain by sedimentary rocks of Mississippian and Pennsylvanian age, which bear abundant fossils, mineral deposits such as iron, as well asnatural gas, coal andpetroleum. These regions fostered 17th-19th century industries locally, even into the 1930s days of mass production. To the south and east of the escarpment/plateau region, the folded mountains and alternating valleys are known as theRidge-and-Valley Appalachians. These extend from the South of the Appalachians to northernNew England except where it is cut by water gaps. InNortheastern Pennsylvania east ofHarrisburg on theSusquehanna River, these ridge and valley features contain the richest and most widespread deposits of high energy clean burninganthracitecoal in the world—theCoal Region—without which theAmerican Industrial Revolution likely would have been delayed or not possible.
In 1859,Edwin L. Drake drilled the first oil well in the U.S. nearTitusville.[2] Similar rock layers also contain coal to the south and east of the oil and gas deposits. In the metamorphic (folded) belt,anthracite (hard coal) is mined nearWilkes-Barre andHazelton. These fossil fuels have been an important resource to Pennsylvania. Timber anddairy farming are also sources of livelihood for midstate and western Pennsylvania. Orchards and vineyards exist along the shore ofLake Erie in the state's far northwest.
During the most recentIce Age, the northeastern and northwestern corners of present day Pennsylvania were buried under the southern fringes of theLaurentide Ice Sheet.Glaciers extended into the Appalachian valleys ofCentral Pennsylvania, but the ice did not top the mountains. At its furthest extent, it spread as far south asMoraine State Park, about 40 miles (64 km) north ofPittsburgh.
Pennsylvania has 57 miles (92 km) ofshoreline along theDelaware Riverestuary, including the busyPort of Philadelphia, one of the largest seaports in the U.S.[3] Chester, downstream, is a smaller but still important port. Thetidal marsh of Pennsylvania's only saltwater shore has been protected asJohn Heinz National Wildlife Refuge at Tinicum.
Pennsylvania also has a narrow inlandfreshwater shore atErie, theGreat Lakes outlet onLake Erie in theErie Triangle.
In the west, thePort of Pittsburgh is large and even exceedsPhiladelphia in rank by annual tonnage because of the large volume of bulk coal shipped bybarge down theOhio River.
Pennsylvania has had several ecological disasters since the 19th century, including:
Pennsylvania has three general climate regions, which are determined by altitude more than latitude or distance from the oceans. Most of the state falls in thehumid continental climate zone. The lower elevations, including most of the major cities, has a moderate continental climateKöppen climate classification (Dfa), with cool to cold winters and hot, humid summers. Highland areas have a more severe continental climate (KöppenDfb) with warm, humid summers and cold, more severe and snowy winters. Extreme southeastern Pennsylvania, aroundPhiladelphia borders ahumid subtropical climate (KöppenCfa), with milder winters and hot, humid summers.
Precipitation is abundant throughout the state with the primary climatic influences being theAtlantic Ocean, theGulf of Mexico, andArctic influences that cross over theGreat Lakes.
