The 6 States That Border Pennsylvania

Known as the Keystone State for its significant location right in the middle of the original 13 colonies, the Commonwealth of Pennsylvania is accessible from many cities on the east coast. Pennsylvania shares a border with six other states: New York, New Jersey, Delaware, Maryland, West Virginia, and Ohio. It also borders Lake Erie. Pennsylvania played a major role in the early days of the American colonies, the American Revolution and independent government, and westward expansion beyond the original 13 colonies. Establishing and keeping borders between Pennsylvania and nearby states went all the way to the Supreme Court in some cases. Now, the Keystone State enjoys a good relationship with its neighbor states. Many cities in Pennsylvania, such as Philadelphia, draw visitors from all over the world.

New York-Pennsylvania Border

At around 225 miles long, the New York-Pennsylvania border has plenty of things to see. These states share a similar climate, especially in this region. Both are mountainous and the stunning Allegheny Mountains are just to the south on the Pennsylvania side. The border has three main sections. The north-south border between Pennsylvania and New York is relatively short and goes from Lake Erie on the northern end to the cornerstone of the Erie Triangle.

The 42nd parallel is the east-west boundary and makes up the majority of the border between Pennsylvania and New York. Experts surveyed and established the border around 1786. However, technology at the time was not 100% accurate so some parts of the border are a bit wobbly compared to the actual 42nd parallel. The final boundary is along the eastern part of the state and follows the Delaware River. It runs south from the 42nd parallel to the Tri-states Monument where Pennsylvania, New York, and New Jersey all meet.

New Jersey-Pennsylvania Border

Moving south, Pennsylvania continues to border New Jersey along the Delaware River. New Jersey and Pennsylvania share roughly 164 miles of waterfrontage on the Delaware River. Although New Jersey has had plenty of land disputes with its neighboring states over the years, New Jersey and Pennsylvania have generally managed to get along. Because the Delaware River forms the border between the two, it is irregularly shaped. But that has possibly made it easier to agree on a boundary, especially in the early days when both states were formed.

Trenton and Philadelphia are major cities along the border of these two states. The majority of Trenton is in New Jersey. Trenton gained fame as the site of George Washington’s first major victory in the American Revolution. General Washington’s famous crossing of the Delaware River took place on December 25, 1776, when he led American troops to Trenton to attack forces there. German painter Emanuel Gottlieb Leutze immortalized it in his piece Washington Crossing the Delaware.

Philadelphia, on the other hand, is mostly in Pennsylvania. It is the largest city in the state and also played an important role in the American Revolution. The Continental Congress met in Philadelphia and signed the Declaration of Independence in the city. Camden, New Jersey is just across the Delaware River from Philly.

Delaware-Pennsylvania Border

The arc-shaped border between Pennsylvania and Delaware is named the Twelve-Mile Circle for its shape and distance. A dispute between New Jersey and Delaware over state boundaries that went all the way to the Supreme Court multiple times formally established boundaries in the area in 1934, including the arc between Pennsylvania and Delaware. It was based on a 1681 land grant from Charles II, then King of England, to William Penn who would later found Pennsylvania. The exact position of the Twelve Mile Circle was based on the tides that would rise around the city of New Castle, Delaware. Though a moderate-sized city on the Delaware River, it is right on the river and in a floodplain. This is the shortest border between Pennsylvania and a neighboring state.

Maryland-Pennsylvania Border

The Mason-Dixon line forms the border between Pennsylvania in the North and Maryland in the South. It is widely recognized as the North-South border of the east coast. Before and during the Civil War, this marked the boundary between slave states in the South and free states in the North. At the time, it extended all the way to Missouri, forming an irregular border between states after it went west from the Pennsylvania-Maryland border. The entire 233-mile Mason-Dixon line was named after the two surveyors who marked it in 1767.

Many disputes arose over the boundary lines between Pennsylvania and Maryland before the formal survey that led to the Mason-Dixon Line. William Penn was granted land which would become Pennsylvania and Cecilius Calvert, 2nd Lord Baltimore, was granted land which would become Maryland. Penn’s grant came from King Charles II in 1681 but Baltimore’s grant came from King Charles I almost 50 years earlier in 1632. Additional land granted to Penn in 1682 fell within the territory claimed by Baltimore. Disputes between the two, their descendants, and the towns that they established continued until the 1750s. The Mason-Dixon line was the final answer to the arguments that lasted almost 100 years. Markers along the border bear the coat of arms of both Penn and Baltimore on their respective sides of the line.

West Virginia-Pennsylvania Border

The east-west portion of the border between Pennsylvania and West Virginia follows the Mason-Dixon line. It runs for 65 miles. Just south of the line are the counties of Preston, Monongalia, and Wetzel. At that point, however, the border turns northward. The north-south boundary goes for around 55 miles until it reaches the Ohio River. This northern panhandle was established in the 1780s after disputes between Pennsylvania and Virginia about which state claimed which portions of the area.

Pittsburgh, Pennsylvania is less than 40 miles from the West Virginia border. This city is the second largest in the state by population, just behind Philadelphia. Like West Virginia, Pittsburgh has an industrial history and played a major role in steel production. It also has a lot of bridges, 466 in total. It is sometimes called the City of Bridges.

Ohio-Pennsylvania Border

The border between Ohio and Pennsylvania runs north-south all the way until it reaches Lake Erie. Surveyor Andrew Ellicott, who was part of the team that completed the surveying for the Mason-Dixon line, mapped the line in 1786. The north-south boundary of Pennsylvania and Ohio is around 92.5 miles. It is named the Ellicott Line after its surveyor.

This boundary is important in the expansion of the United States. Up to that point in American history, land grants given by the King determined the majority of boundaries between colonies, which became states. Although some were disputed well beyond that time, they had their origins in colonial America. Establishing borders between Pennsylvania, Virginia, and nearby colonies with land further west marked the beginning of westward expansion. Rather than land grants from the King, these boundaries were established and recognized by the American government and states. This signified an important turning point in American history.