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• Mason-Dixon line
  Mason-Dixon line

  noun

  the boundary between Pennsylvania and Maryland, partly surveyed by Charles Mason and Jeremiah Dixon between 1763 and 1767, popularly considered before the end of slavery as a line of demarcation between Free States and Slave States.
• Mason-Dixon Line
  Mason-Dixon Line

  noun

  the state boundary between Maryland and Pennsylvania: surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon; popularly regarded as the dividing line between North and South, esp between the free and the slave states before the American Civil War

Mason-Dixon line

American  

[may-suhn-dik-suhn] / ˈmeɪ sənˈdɪk sən /

Also Mason and Dixon line

noun

1. the boundary between Pennsylvania and Maryland, partly surveyed by Charles Mason and Jeremiah Dixon between 1763 and 1767, popularly considered before the end of slavery as a line of demarcation between Free States and Slave States.

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Mason-Dixon Line British  

/ ˈmeɪsə n ˈdɪksən /

noun

1. the state boundary between Maryland and Pennsylvania: surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon; popularly regarded as the dividing line between North and South, esp between the free and the slave states before the American Civil War

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Mason-Dixon line ¹ Cultural  

1. A boundary line between Pennsylvania and Maryland, laid out by two English surveyors, Charles Mason and Jeremiah Dixon, in the 1760s. Before and during the Civil War, the line was symbolic of the division between slaveholding and free states. After the war, it remained symbolic of the division between states that required racial segregation and those that did not.

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Mason-Dixon line ² Cultural  

1. Part of the boundary between Pennsylvania and Maryland established by the English surveyors Charles Mason and Jeremiah Dixon in the 1760s. The line resolved disputes caused by unclear description of the boundaries in the Maryland and Pennsylvania charters.

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Though the line did not actually divide North and South, it became the symbolic division between free states and slave states. Today, it still stands for the boundary between northern and southern states.

Etymology

Origin of Mason-Dixon line

An Americanism dating back to 1770–80

Example Sentences

See Examples For:

Mason-Dixon line Mason-Dixon Line

And with all due respect to the people of the Lone Star State, I think it’s time for a season somewhere north of the Mason-Dixon line.

From Los Angeles Times ● Oct. 13, 2023

The change was particularly pronounced in a swath from about the Mason-Dixon line to just north of Detroit, Chicago, and Nebraska.

From Washington Times ● Dec. 17, 2021

But both rulings were widely ignored below the Mason-Dixon line, prompting civil rights activists to draw attention to the states' continuing segregation.

From Salon ● Apr. 24, 2021

Dixie is thought to be a reference to the Mason-Dixon line, although the origins of the term are still debated by historians.

From New York Times ● Jan. 20, 2020

On the map, the division line between slave and non-slave societies occurs in Virginia, broadly anticipating the Mason-Dixon line that later split slave states from free.

From "1491" by Charles C. Mann

My parents insisted I apply to colleges below the Mason-Dixon Line and on the east side of Texas.

From The Wall Street Journal ● Jan. 20, 2026

That prompted the Maryland Legislature to pass a public accommodations law in 1963 banning discrimination in hotels and restaurants, becoming the first state below the Mason-Dixon Line to do so.

From Seattle Times ● Jun. 7, 2023

They are consumed with gusto and discrimination at nearly every party you might attend south of the Mason-Dixon Line, and although oblong and a bit thicker, they're sort of the grown-up version of a Cheez-It.

From Salon ● Jan. 22, 2023

A Black Democrat who served as governor and lieutenant governor south of the Mason-Dixon Line.

From Washington Times ● Nov. 12, 2021

Substance, in her opinion, came with a soulful name and lay south of the Mason-Dixon Line.

From "Hope Springs" by Jaime Berry