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Mason-Dixon Line
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Map showing the Mason-Dixon Line as a solid red line marking the boundary between Maryland and Pennsylvania, with a dashed red line extending westward along the Ohio River to represent its unofficial extension separating free and slave states before the U.S. Civil War. Current state boundaries are outlined in gray. Mason-Dixon Line
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Mason-Dixon Line: References & Edit History

Article Contributors

Primary Contributors

  • The Editors of Encyclopaedia Britannica
    Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.

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Article History

Type Description Contributor Date
Invalidated site: The Delaware Geological Survey - The Mason-Dixon Line, that land is your land. Aug 27, 2026
Add new Web site: Historic UK - Charles Mason and Jeremiah Dixon, Surveyors of the Mason-Dixon Line. Sep 12, 2025
Add new Web site: ExplorePAhistory.com - Mason-Dixon Line Historical Marker. Jun 07, 2025
Add new Web site: NPR - A Journey Below The Mason-Dixon Line. Apr 23, 2025
Add new Web site: BBC - The men who drew the Mason-Dixon Line. Jan 17, 2025
Add new Web site: Harvard University Press - The Mason-Dixon Line—America’s Great Divide. Oct 29, 2024
Add new Web site: The Delaware Geological Survey - The Mason-Dixon Line, that land is your land. Nov 08, 2023
Add new Web site: Maryland Center for History and Culture - When Maryland Almost Got Philadelphia: The Remarkable Story of the Mason-Dixon Line. Aug 18, 2023
Add new Web site: American Heritage - Mason and Dixon: Their Line and its Legend. Apr 01, 2023
Add new Web site: History Cooperative - The Mason-Dixon Line: What Is It? Where is it? Why is it Important? Feb 19, 2023
Add new Web site: Explore PAHistory - Mason-Dixon Line. Nov 28, 2022
Changed the title from “Mason and Dixon Line” to “Mason-Dixon Line.” May 04, 2020
Media added. Oct 01, 2015
Add new Web site: Social Studies for Kids - The Mason-Dixon Line. Jul 03, 2015
Add new Web site: The Encyclopedia of Greater Philadelphia - Mason-Dixon Line. Jul 03, 2015
Add new Web site: Pennsylvania Center for the Book - Our Most Famous Border: The Mason-Dixon Line. Jul 03, 2015
Add new Web site: ExplorePAhistory.com - Mason-Dixon Line. Jul 03, 2015
Article revised and expanded. Jun 01, 2015
Added new Web site: How Stuff Works - History - Mason and Dixon's Line. Nov 07, 2008
Added new Web site: Robert B. Van Atta - The Mason-Dixon Line. Feb 07, 2007
Added new Web site: Otto Sell - Mason-Dixon Line. Feb 07, 2007
Added new Web site: Civilwarhome - The Mason-Dixon Line. Feb 07, 2007
Added new Web site: Jeffrey C. Weaver - Evolution of the Mason-Dixon Line. Feb 07, 2007
Added new Web site: Mason-Dixon Arrive - Mason-Dixon Line. Feb 07, 2007
Article revised. Feb 08, 1999
Article added to new online database. Jul 20, 1998
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