The line was named after two British surveyors, Charles Mason and Jeremiah Dixon.
They were hired by two prominent families on either side of the border, both were originally headed by Oxford alumni:
- Catholic Leonard Calvert, founder of slave-colony Maryland. Leonard's brother Cecil, the second Lord Baltimore, handled the British end of the formation of the colony. Leonard and Cecil, as well as their father George–the first Lord Baltimore–were all alumni of Trinity College, Oxford.
- Quaker William Penn, founder of free-colony Pennsylvania. William Penn was an alumnus of Christ Church, Oxford.
The essential element of their survey, which had been interrupted by skirmishes with Indians, was completed on this day.
It established the boundary not only between the colonies of Pennsylvania and Maryland but for territories in the west that after the Revolution became the state of West Virginia and those in the east that became Delaware. The line was marked using stones, with Pennsylvania’s coat of arms on one side and Maryland’s on the other.
Why did this become the dividing line in the War Between the States? Because it was the North-South dividing line, between the slave states in the south and the free states in the north.
It is no puzzle why the South favored slavery–the earliest immigrants to the southern colonies like Virginia were loyalists to the British Crown and the Church of England and they were given generous grants of land that required huge numbers of workers. The cash crops such as tobacco and cotton that became the mainstay of the southern farms required workers to do strenuous repetitive tasks, and slavery provided a solution.
It is also no puzzle why New England did not favor slavery. They did not get large grants of land from the Crown because the earliest immigrants to New England were dissenting rebels from the Church of England. Most therefore became small farmers, traders or manufacturers.
Maryland and Pennsylvania were in-between colonies and states. Unlike most other southern states (Georgia's Wilberforce was another exception), Maryland was not founded by someone with allegiance to the Church of England. Even though Pennsylvania was not founded by a dissenting Quaker, its founder Penn had enough good will from the Crown to get some land to form a proprietary colony:
- In Maryland, the Crown carved a large piece of land out of northern Virginia to give to the Catholic Calverts. The Catholicism of the day was not aggressively opposed to slavery.
- In Pennsylvania (as it was to be called), lands were granted to Quaker William Penn because he had won favor with the Crown, even though leaders of his religion included many abolitionists who fought actively against slavery. It was easier in Pennsylvania than it was in Maryland to be opposed to slavery because of coal and iron reserves provided higher-paying jobs that did not have to rely on slavery to generate a competitive product.
Both families claimed the land between the 39th and 40th parallels. Mason and Dixon established the border at 39º43'. If they believed that the rights on the two sides were equally balanced, they would have settled in the middle, at 39º30'. This suggests that Pennsylvania was the victor from the survey, getting 72 percent (43/60) of the disputed land area.
During the year 1767, the colonies were engaged in a dispute with the Parliament over the Townshend Acts, which sought–through taxes on tea and other imports–to pay for the British costs of troops sent by Prime Minister William Pitt the Elder (like the Calverts, an alumnus of Trinity College, Oxford) of establishing the continuing military presence that had driven the French and the Indians allied with them from the colonies.
However, the border dispute seemingly settled in 1767 was not over. The Mason-Dixon line held as a dividing line, but after the American Revolution, the states south of the Mason-Dixon line began lobbying the new U.S. Congress for the legal rights of slaveowners. The northern states argued that ownership of human beings was not acceptable in the "New Constellation" of states.
Although the arguments were temporarily ended by the Missouri Compromise of 1820, which accepted the states south of the Mason-Dixon line as slave-holding and those north of the line as free, the attempted compromise–and its successors–failed and Pennsylvania became the site of many famous Civil War battles. The Gettysburg, Pennsylvania battle in 1863 was on the Mason-Dixon Line. It was one of the bloodiest battles of the American Civil War, made immortal by President Lincoln's speech at the site . The Quaker commitment to abolitionism trumped their commitment to peace.
In April 1865, the south capitulated. The ensuing 13th Amendment (1865) was immediately passed abolishing slavery and nullifying the Supreme Court's Dred Scott decision (1857). The bitterly fought 14th Amendment gave citizenship to all persons born or naturalized in the United States. It was ratified 101 years after the Mason-Dixon line was established. However, civil rights did not mean voting rights. It took many more debates and political battles, some more amendments, and another 100 years, for the United States to pass laws to ensure that all adult citizens be allowed to vote...