Ohio

Seneca

55,069
2020 population
1830
first census record
20
census records

About Seneca

Seneca, Ohio, first appears in the United States federal census in 1830, when it recorded a population of 5,159. At the most recent census, in 2020, its population stood at 55,069.

Its recorded population peaked at 61,901 in 1980, and has since declined by roughly 11 percent.

On the ground today, 2 documented military engagements have been recorded within the county, among them Fort Sandusky Massacre (Pontiac's War 1763), Skirmish at Sandusky Plains (Crawford's approach, 1782), and 46 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
202055,069
201056,745
200058,683
199059,733
198061,901
197060,696
196059,326
195052,978
194048,499
193047,941
192043,176
191042,421
190041,163
189040,869
188036,947
187030,827
186030,868
185027,104
184018,128
18305,159
Source

Population data from the United States decennial census, U.S. Census Bureau (public domain).

Battles & engagements in Seneca

Military engagements that took place in Seneca, Ohio.

Fort Sandusky Massacre (Pontiac's War 1763)
1763
Skirmish at Sandusky Plains (Crawford's approach, 1782)
1782

Historic places in Seneca

National Register of Historic Places listings in Seneca, Ohio.

National Home, Daughters of America
Tiffin
Octagon, The
Tiffin
Michaels Farm
Kansas
Bagby-Hossler House
Tiffin
St. Boniface Roman Catholic Church, School, Rectory, and Convent of the Sister of the Precious Blood
New Riegel
Omar Chapel
Attica
Aigler Alumni Building
Tiffin
Browse all Ohiohistoric sites ›

Other counties in Ohio

Explore census history and historic records for more Ohio counties.

AshlandAshtabulaAthensAuglaizeBelmontBrownButlerCarrollChampaignClarkClermontClintonColumbianaCoshoctonCrawfordCuyahogaDarkeDefianceDelawareErie
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Everything a full report reveals about Seneca County, Ohio

This page charts the census history of Seneca County, Ohio. A full Aubrey report for an address here pulls together everything the historical record holds about the ground, from the earliest settlement to the twentieth century:

Overview
An interactive map of the location with historic sites, battles and Native heritage plotted, and its full story era by era.
The Land
The historic sites and place names around the location, and how this land was settled and used.
Geology
The bedrock beneath the site, its age and rock type, reaching back millions of years.
LiDAR Terrain
Laser-scanned terrain that reveals earthworks and old features hidden in the landscape.
Conflict & War
The battles, raids and skirmishes fought near here, across every era of American conflict.
The Civil War
The Civil War on this ground, 1861 to 1865: who held it, and the battles, camps and regiments nearby.
The Soldiers
The men who marched from here in the Civil War, named and traced where the record allows.
Native Heritage
The Native nations who held this land, mapped across time from before European contact to today.
Settlement
Who claimed and held this ground, from Indigenous homelands through the colonial powers to the United States.
The Community
How the town grew, who came, and what kind of place it became, traced through the census record.
Rivers & Rail
The rivers, canals and railroads that connected this place between 1830 and 1911.
Notable People
The people born, buried or genuinely tied to this exact place, with their stories.
Historical Maps
Historic maps of the location layered over how it looks today.
Finds & Access
Museum objects tied to the area, and the laws on searching, collecting and access here.
Literature
The old books, county histories and archives that mention this place, quoted with their sources.
Spotlight
A deep dive into the most remarkable, lesser-known history of the place, traced back to the record.
Points of Interest
The most significant historic sites and landmarks near the location, and why they matter.
Timeline
The whole story of the location told era by era, from first peoples to the present day.
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Frequently asked about Seneca

When does Seneca first appear in the US census?
Seneca, Ohio first appears in the federal census in 1830, with a recorded population of 5,159.
What is the population of Seneca?
At the most recent federal census (2020), Seneca had a recorded population of 55,069.
When did Seneca's population peak?
Seneca's recorded population peaked at 61,901 in 1980.
Were any battles fought in Seneca?
2 documented military engagements took place in Seneca, including Fort Sandusky Massacre (Pontiac's War 1763), Skirmish at Sandusky Plains (Crawford's approach, 1782).
How many historic places are in Seneca?
46 sites are listed on the National Register of Historic Places in Seneca, Ohio.
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