The Mason-Dixon Line is probably the most famous border survey in the world, and also the most misunderstood. Most people today see it as the historical dividing point between the 'free' North and the 'slave-holding' South in Colonial America. It was actually just a civilized method to solve a border dispute. The rest came later.

Maryland, My Maryland¹

In 1625 King James I granted George Calvert the title of Lord Baltimore, even though he had declared himself a member of the Catholic church and was consequently forced to resign his post as the King's secretary. He was also given a large tract of land in Newfoundland (now a province of Canada). After spending a winter in his new territory Lord Baltimore felt the climate was too harsh for a successful colony. He requested a different area for his people, just to the north of the Virginia Colony.

Charles I had become King after his father's death in 1625. Before Charles could complete the charter George Calvert also passed away. The new land charter was granted to George's son Cecil, 2nd Lord Baltimore, in 1632 for a colony that was designated as the land between Virginia and the 40th parallel.

Lord Baltimore and his people began their colony on Chesapeake Bay, even though their charter extended to 'the Bay of Delaware'. In 1631 a group of Dutch colonists had formed a settlement near Delaware Bay, but when their sponsors returned the following year they found the settlement burned and the people killed in an attack by the 'Indians'. The eastern area of Lord Baltimore's land remained unsettled except for the Native Americans until a group from Sweden arrived in 1638 and built a colony near present day Wilmington, Delaware. The colony prospered until 1655 when Peter Stuyvesant arrived and took control of the entire area for the Dutch as a part of the 'New Netherlands'.

Between 1649 and 1660 there was a disruption of the British government affectionately known as the 'Interregnum' – the time between kings. Oliver Cromwell, and sometimes the Parliament, ruled England. Then Charles I's son became King Charles II. A major war was fought in Europe and in 1674 the Dutch ceded all their land in North America to England.

Penn's Woods²

Charles II granted the land to the north of Maryland to William Penn in 1681. In another charter William Penn was instructed to create a city 'in the most convenient place, upon the river, for health and navigation'. Unfortunately the site selected for the city of Philadelphia, at the junction of the Schuylkill³ and Delaware rivers, was located at the latitude of 39° 57' north. This was technically inside the territory that had been granted to Lord Baltimore.

Both Penn and King Charles thought the the 40th parallel was further south than its true position. Part of this confusion was based on the south eastern border being established by an arc of the 12 mile (19km) circle drawn from the spire of the courthouse of the existing town of New Castle on the Delaware River - the town was actually located at the latitude of 39° 40' north, or 23 miles (37km) south of the 40th parallel.

This would be the cause of a major border dispute between the two colonies for many years to come.

The entire border conflict was further confused when William Penn was granted 'the three lower counties' - land below the '12 mile circle'. Although this area had originally been been a part of the Maryland charter, its claim had been usurped by the foreign occupation. Penn's request to expand his colony was granted.

What did Della Ware?⁴

In 1701 William Penn established representation for each of his counties and allowed them some independence. The people of the three lower counties (in what we now call Delaware) had little in common with the counties to the north - they became a semi-independent entity from the early 1700s. Delaware was still a legal part of Pennsylvania at that time⁵, and its counties shared a common governor with the northern counties, but the three lower counties had their own legislature. Pennsylvania had two delegations in the Continental Congress, one representing the upper counties and the other the three lower ones.

In the 1730s violence began to erupt along the disputed border between the Catholics of Maryland and the Protestants of Pennsylvania and Delaware. After many years the army had to be called in to stop the conflict – King George III finally demanded that the border be properly established.

Mason and Dixon

Charles Mason was a British astronomer who had been trained at the Greenwich Observatory near London, England. He first met Jeremiah Dixon, a professional surveyor and amateur astronomer when they were both employed to observe the transit of Venus in 1761. Although they did not reach their intended destination of Sumatra, they did record their observations from the Cape of Good Hope, South Africa.

Why was an Astronomer Involved in a Survey Project?

The entire theory of a land survey is to start from a known spot on the face of the earth, and then accurately measure the distance and angle to the next point. In an unknown region, as was the area surrounding Philadelphia in 1763, the only way known to locate your true starting point was by accurate stellar observations. At several points during the survey astronomical observations were used to confirm the measurements that had been made, and their current position.

The Survey

In 1763 the two men entered into an agreement with Thomas Penn and Fredrick Calvert, representing Pennsylvania (including Delaware) and Maryland respectively, to accurately mark the border between their colonies. The starting point was to be 15 miles (24km) south of the southernmost house in Philadelphia. This point was placed at approximately 39° 43' north latitude, 20 miles (33km) south of the border that had been granted to Lord Baltimore.

There were 'Crown-shield' markers placed at regular intervals along the line, bearing both the Penn and Calvert coats of arms, each facing their respective territories. The first point established was the north east corner of Maryland; they placed a monument at this point for later reference. The first part of the line ran a short distance due south until it met the '12 mile circle' at a tangent, where it veered slightly to the east⁶. When they reached the southern border that had been agreed upon they turned east until they met the sea, continuing across to the barrier islands.

In April 1765 they returned to their starting point and began the long line to the west. The original termination was to be a full 5° west of the Delaware River, 265 miles (426km) at that latitude. When they crossed the line drawn due south from the source of the Potomac River, the land to the south became Virginia⁷. Travelling through the wilderness, crossing rivers and high mountains, they cut a line of sight 8 to 12 yards (7 to 11 metres) wide. It marked their progress on the landscape. The Native Americans, specifically the Iroquois, objected to this destruction of their land and threatened violence if the survey continued. After marking only 233 miles (375km) of the border the survey was abandoned and the two men returned to England on 11 September, 1768. The three legs of the survey are still known today as the Mason-Dixon Line. The two men would never again share an assignment.

The Peculiar Institution

Americans do not like to say the word 'slave'. They are referred to in the US Constitution as 'other persons'. In the 18th and 19th centuries everyone knew that 'the peculiar institution' meant the enslavement of black people. Although the 'institution' was not as prevalent in most northern colonies as it was in the south, at the time of Mason and Dixon's survey there was not a single 'free' area in the British American colonies. Even Canada recognized some slavery until 1834. After the Declaration of American Independence many of the northern states began to reduce or eliminate slavery. When Pennsylvania outlawed slavery within its borders in 1781, the Mason-Dixon line became the de-facto line between the slave states and a free state. Delaware, which was both east and north of the line, continued to support slavery, although never to a large extent. Slavery was only completely outlawed in Delaware by the ratification of the 13th Amendment to the US Constitution in 1865. Maryland had stopped the practice in the previous year with a new state constitution. Both states remained with the Union throughout the American Civil War.

In the years leading up to the American Civil War the states above the Mason-Dixon line had all become 'free' states and had no slavery, and all of the states south of the line had a slave economy. If an escaping slave could cross the line (into Pennsylvania, or to a lesser extent, Delaware) they would be relatively safe, especially among the Amish and Quaker peoples of Southern Pennsylvania.

People such as Harriet Tubman and other conductors on what was called the 'Underground Railroad'⁸ would take groups of slaves to freedom across this line, or the Ohio River, where they could then move on to other points further north.

As the country grew in its westward expansion so did the concern over the number of free and slave states. Both sides thought that if the others gained a majority, laws would be passed that would force the entire country one way or the other. In 1820 the 'Missouri Compromise' set an artificial line at latitude 36° 30' as the new dividing point - no state north of this line, with the exception of Missouri, would be allowed to own slaves, while those to the south of the line could support the slave culture. This was negated by the Kansas–Nebraska act. The final result was the bloody conflict that Mason and Dixon had hoped to avoid, albeit with different parties, and political concerns, involved.

You Ain't Just A–Whistling Dixie?⁹

Today the southern United States are collectively identified as Dixie. The song of the same name was written in 1859 by a composer from the State of Ohio (a Northern State that staunchly stood with the Union) named Daniel Emmett. The true origin of the name 'Dixie' has been lost in the mists of time. Some claim it came from a ten pound note that was issued by a bank in New Orleans that carried the word 'dix', French for ten. Others accredit it to Jeremiah Dixon himself. In any event the song became the unofficial anthem for the South during the war and is probably one of the reasons that Mason and Dixon remain so well remembered today.

The Mason-Dixon line remains as the legal boundary between the states, and determines which laws must be followed and who may collect the taxes.

If you find yourself wandering the back country of northern Maryland or southern Pennsylvania and spot an old stone sprouting from the ground, you now understand who put it there and why. Many still consider the Mason-Dixon line as the boundary between the easy-going ways of the South and the fast paced life in the North.