PLACE / TIME / EVIDENCE
Same place.
Different county.
Follow Ohio’s changing county lines. Find the jurisdiction, read what changed, and choose your next place to research.
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View cropped to modern Ohio. Historical counties sometimes extended beyond this frame. Shapes are generalized, not property boundaries. NCA = non-county area. Labels thin automatically to reduce overlap.
THE PAPER TRAIL
County chronology
Includes organization and attachment events that may not change the drawn boundary.
WATCH THE CHANGES
Ohio through time in 28 seconds.
A silent, captioned illustration of the explorer’s historical data. Use the controls above to investigate an exact date.
Read the demonstration transcript
Ohio’s county boundaries changed over time. Solid lines show historical counties; dashed lines show the 2024 comparison. By the end of the historical dataset in 2000, there are 88 counties. Compare February 28 and March 1, 1818: Perry County was formed from Fairfield, Muskingum and Washington. Choose a date, read the cited change and confirm who holds the records today.
SOURCE NOTES
A map is a starting point.
Historical evidence
Peggy Tuck Sinko, Ohio Historical Counties, digital compilation by Laura Rico-Beck, edited by John H. Long. Newberry Library, 2010. Coverage: December 9, 1778 through December 31, 2000. Event descriptions and citations are retained from the dataset.
Open Newberry’s Ohio atlas ↗ · Bibliography ↗ · Historical commentary ↗
What the lines cannot tell you
A county could exist before it operated independently. Read its dated attachment and organization notes. A historical jurisdiction does not establish which repository holds a record today.
The map represents the atlas’s colonial, territorial and state administrative claims. It is not a map of Indigenous nations, land ownership or a complete account of sovereignty.
Modern comparison: U.S. Census Bureau, 2024 generalized counties ↗. This is a dated reference layer, not a verified 2026 boundary survey.
Data treatment, exceptions and reuse
Historical polygons are clipped to the modern Ohio footprint and simplified to 0.001 degrees for display. Coordinates are plotted at an Ohio overview scale; one invalid source geometry was repaired during conversion. Original downloaded files are retained separately. Near-boundary questions require the source descriptions and more detailed maps.
Two small Cuyahoga–Geauga changes are listed in the source but are too small to draw reliably: January 29, 1841, and January 11, 1843. The chronology retains them. The compiler also explains interpretive decisions involving the Seneca Gore and the Morgan–Washington boundary in the commentary.
Newberry’s current reuse statement specifies CC0. Its download page says older license notices included in the files are superseded. Reviewed October 26, 2026. No claim is made that Brick Wall Protocol independently rechecked every cited law.