250th Anniversary of the Mason-Dixon Line

On this day, 250 years ago—9 October 1767, the survey of the Mason-Dixon line was completed.

Starting in the early 1700s, my Noel-Ardinger and Taylor-Thomas lines and my spouse’s Spangler family settled in southern Pennsylvania and northern Maryland: Adams, Cumberland, Franklin, Lancaster, and York Counties, Pennsylvania and Carroll, Frederick, and Washington Counties, Maryland—on or near the Mason-Dixon line.

The Mason-Dixon line came about because the Colonies of Maryland and Pennsylvania both claimed the land between the 39th and 40th parallels according to the charters granted to each. Maryland had been granted the territory north of the Potomac River up to the 40th parallel. Pennsylvania’s grant defined the colony’s southern boundary as following a 12-mile circle counter-clockwise from the Delaware River until it hit “the beginning of the 40th degree of northern latitude.” From there, the boundary was to follow the 40th parallel due west for five degrees of longitude. But the 40th parallel did not intersect the 12-mile circle, instead it was significantly farther north. Thus, Pennsylvania’s southern boundary, as defined in its charter, was unclear and contentious, placing Philadelphia, Pennsylvania’s major city, within Maryland’s domain.

In 1732, Proprietary Governor of Maryland Charles Calvert, 5th Baron Baltimore, signed an agreement with the sons of William Penn establishing the border somewhere between the areas of contention and renouncing the Calvert family’s claim to Delaware. However, soon thereafter, Lord Baltimore claimed that the document he signed did not contain the terms to which he had conceded; therefore, he refused to abide by the terms of that agreement.

In the mid-1730s, violence erupted between the Maryland and Pennsylvanian settlers; this border conflict became known as Cresap’s War.

In 1760, this issue remained unresolved, forcing the English Crown to intervene. George III ordered Frederick Calvert, 6th Baron Baltimore, to accept the 1732 agreement, as written.

In 1763, as part of the settlement, the Penns and Calverts commissioned English Astronomer Charles Mason and Surveyor Jeremiah Dixon to confirm the newly established boundaries between Pennsylvania, Maryland, Delaware, and Virginia. The Calverts and the Penns paid Mason and Dixon 1 pound, 1 shilling per day to have 244 miles surveyed. (By the end of the project, a total of £3,512/9 s—3,512 pounds, 9 shillings—was paid.)

The most difficult task for Mason and Dixon was determining the tangent line, as they needed to confirm the accuracy of the transpeninsular line midpoint and the 12-mile circle, determine the tangent point along the circle, and survey and mark the border. (Unfortunately, this left a small wedge of land which was disputed between Delaware and Pennsylvania; this land remained in contention until 1921.)

In April 1765, Mason and Dixon began their survey of the Maryland-Pennsylvania line, an east-west border with an approximate mean latitude of 39°43’ 20” N.

The Mason-Dixon line was defined by marker stones every mile with crown stones every five miles. These stones were quarried in England. The marker stones on engraved with an M on the Maryland side and a P on the Pennsylvania/Delaware sides. The crown stones were marked with the Calvert coats of arms on the Maryland side and the Penn coat of arms on the Pennsylvania side.

Mason and Dixon’s survey was finished on 9 October 1767, ending approximately 31 miles east of Pennsylvania’s southwest corner.

After Pennsylvania abolished slavery in 1781, the western part of the Mason-Dixon line and the Ohio River became a border between free and slave states, although Delaware remained a slave state.

The line has been resurveyed three times since the original survey (1849, 1900, and during the 1960s) with very few changes to the original findings by Mason and Dixon. Full details about the 1900 resurvey can be found here.

This slideshow requires JavaScript.

#americanhistory    #englishhistory    #familyhistory

Categories: Famous Faces and Places, Noel-Ardinger Line, On This Day, Spangler-Kenney Line, Taylor-Thomas Line | Tags: , , | 4 Comments

Post navigation

4 thoughts on “250th Anniversary of the Mason-Dixon Line

  1. Pingback: Conflict in Our Family Trees | Princes, Paupers, Pilgrims & Pioneers

  2. Pingback: *Press it* 250th Anniversary of the Mason-Dixon Line | Its good to be crazy Sometimes

  3. Interesting article…loved the pics!

    Liked by 1 person

  4. Love this! Thank you so much for sharing.

    Liked by 1 person

Please share your thoughts...

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a website or blog at WordPress.com

Sheila's Archive

A Family History

Anna's Musings & Writings

A Catholic and Aspiring Contemplative's Journey, Genealogy, Odds and Ends . . .

Rhos Helyg Family History Services

Follow my family history adventures and more

Personal Prologue: Family Roots and Personal Branches

Copyright©2022, Margo Lee Williams, All Rights Reserved

Once Upon A Lifetime: Tales And Vignettes Of My Ancestors

MaryAnne Slabik-Haffner, Family History Author

Rhyme Schemes and Daydreams

Things That Interest Me

The Chiddicks Family Tree

Every Family has a story to tell..........Welcome to mine

writing my past

in which I document my genealogical research adventures and explore the people and events from my family's history…

Deeper Roots Genealogy

~ Discovering Your Family's Past To Shape Your Future ~

Delving into the past

Here you shall find, my writings, about my family research, and general research into murders, and other people's ancestry, where I dig deep, and find all kinds of information about my family, whether it is good or bad, and my life itself in general, there are some sad, informative, facts here, which I hope, will get you guys blogging, so what are you waiting for? Get reading!

A Pennsylvania Dutch Genealogy

the genealogy & family research site of Kris Hocker

The Family Letter Blog

Connecting Generations

Discovering Yesterday

Preserving the history of ordinary people

Barb's GeNealogy Life

Combining two of my favorite addictive pastimes - family history and writing.

Past Presence

A site for genealogists and family historians

Julie's Genealogy & History Hub

Blog of Brass Oak Genealogy

The Family Kalamazoo

A genealogical site devoted to the history of the DeKorn and Zuidweg families of Kalamazoo and the Mulder family of Caledonia

From Shepherds and Shoemakers

Sharing musings, insights, resources and strategies as I discover my family history.

Its good to be crazy Sometimes

A view from the inside of going through the minefield of the British benefit system if you are disabled and the ups and downs of coping with mental illness


Words of wisdom, inspiration, feeling

Rants, Rambles, Revelations, Remembrances

Because the voice in my head won't stay silent...

Genealogy for Children

How to engage children in genealogy and family history

Brumley Family Branches

A Genealogy Blog


Collecting stories from family historians who are climbing their family trees and planning trips to where their ancestors actually lived!

Kindred Stories

Everyone has a story


Where Distant Family Become Close

Jill's Garden

Garden of Life

Chips Off the Old Block

A blog devoted to genealogical wanderings - dedicated to family near and far, through distance and time

Applegate Genealogy

Helping others discover their roots

Gary A Wilson Stories

10 Minute Adventures, Fiction and Coffee Breaks

Shaking The Branches

Sharing Stories From My Family Tree

Decoding the Family Tree

solving family history one branch at a time.

Bespoke Genealogy

UK and Ireland: Genealogy, History and Travel

The Letters

Louise Mabey

From Ballachulish to South Mississippi

Mississippi family history letters


Exploring the Past to Improve the Future

Aquila's Place

An Eccentric Mix of Literature and Opinions

The Women Who Made Me

Finding the extraordinary in the ordinary

F Yeah History

History...but better

Amanda Bradburn

Author | Editor | Genealogist | Historian


Actor, Writer, and Embroidery Artist seeking beauty and humour.

Today in History

"Tell me a fact, and I'll learn. Tell me a truth, and I'll believe. But tell me a story, and it will live in my heart forever." - Steve Sabol, NFL Films

Empty Branches on the Family Tree

Genealogy Tips & Family History

Dusty Roots & Forgotten Treasures

Researching, Preserving, and Sharing Genealogical Information For Future Generations

%d bloggers like this: