New York

Ontario

112,458
2020 population
1790
first census record
24
census records

About Ontario

Ontario, New York, first appears in the United States federal census in 1790, when it recorded a population of 1,075. At the most recent census, in 2020, its population stood at 112,458.

The county's recorded population has risen across the decades to its highest level in 2020.

On the ground today, 6 documented military engagements have been recorded within the county, among them Seneca Lake Fortified Iroquois Village, Seneca Fortified Village – Rochester Junction, Morse Site Fortified Village – Ontario County, and 79 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
2020112,458
2010107,931
2000100,224
199095,101
198088,909
197078,849
196068,070
195060,172
194055,307
193054,276
192052,652
191052,286
190049,605
189048,453
188049,541
187045,108
186044,563
185043,929
184043,501
183040,288
182088,267
181042,032
180015,218
17901,075
Source

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

Battles & engagements in Ontario

Military engagements that took place in Ontario, New York.

Seneca Lake Fortified Iroquois Village
1400
Seneca Fortified Village – Rochester Junction
1440
Morse Site Fortified Village – Ontario County
1450
Seneca Nation Warfare Sites
1450
Boyd and Parker Ambush
1779
Destruction of Canandaigua (Sullivan Campaign)
1779

Historic places in Ontario

National Register of Historic Places listings in Ontario, New York.

Cronkite, Jeremiah, House
Victor
Parrott Hall
Geneva
St. Peter's Episcopal Church
Bloomfield
Seneca Presbyterian Church
Stanley
Cleveland, Ephraim, House
Naples
Clifton Springs Sanitarium Historic District
Clifton Springs
Geneva Armory
Geneva
Valentown Hall
Victor
Geneva Hall and Trinity Hall, Hobart & William Smith College
Geneva
North Main Street Historic District
Canandaigua
Wheeler, George and Addison, House (Additional Documentation)
East Bloomfield
Harmon Cobblestone Farmhouse and Cobblestone Smokehouse
Phelps
Huffman, William, Cobblestone House
Phelps
Adelaide Avenue School
Canandaigua
Clifton Springs Sanitarium
Clifton Springs
Morgan Hook and Ladder Company
Naples
Farmington Quaker Crossroads Historic District
Farmington
Farmers and Merchants Bank
Geneva
Sonnenberg Gardens
Canandaigua
Rippey Cobblestone Farmhouse
Seneca
St. John's Episcopal Church
Phelps
Boughton Hill
Victor
Canandaigua Historic District
Canandaigua
Wheeler, George and Addison, House (Boundary Increase)
East Bloomfield
Browse all New Yorkhistoric sites ›

Other counties in New York

Explore census history and historic records for more New York counties.

OrleansOswegoOtsegoPutnamQueensRensselaerRichmondRocklandSaratogaSchenectadySchoharieSchuylerSenecaSt. LawrenceSteubenSuffolkSullivanTiogaTompkinsUlster
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Everything a full report reveals about Ontario County, New York

This page charts the census history of Ontario County, New York. 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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Explore New York records

New Yorkhistory ›NRHP historic sites ›Notable people from New York›

Frequently asked about Ontario

When does Ontario first appear in the US census?
Ontario, New York first appears in the federal census in 1790, with a recorded population of 1,075.
What is the population of Ontario?
At the most recent federal census (2020), Ontario had a recorded population of 112,458.
Were any battles fought in Ontario?
6 documented military engagements took place in Ontario, including Seneca Lake Fortified Iroquois Village, Seneca Fortified Village – Rochester Junction, Morse Site Fortified Village – Ontario County.
How many historic places are in Ontario?
79 sites are listed on the National Register of Historic Places in Ontario, New York.
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