County · code 36041
Hamilton CountyNew York
Hamilton County is in New York and has its county seat at Lake Pleasant. The county was created in 1816.
- Founded1816
- County seatLake Pleasant
- Named forAlexander Hamilton
- Land area1,717 sq mi + 90 sq mi water
- Population5,107 2020 Census
- Parcels mapped12,947 checked 15 October 2026
Where it is
Hamilton on the map of New York
New York has 62 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1816 from Montgomery County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Hamilton County was created from Montgomery County on April 12, 1816, but was not fully organized at first and remained attached to Montgomery for administrative and judicial purposes. The county was partially organized and detached from Montgomery in 1838, then fully organized by summer of 1847. Hamilton gained territory from Fulton County in 1860 and exchanged territory with Essex County in 1915.
- 1816Hamilton County created Hamilton created from Montgomery; Hamilton not fully organized, attached to Montgomery for administrative and judicial purposes. · N.Y. Laws 1816, 39th sess., ch. 120, sec. 1/p. 119
- 1838Changed Hamilton was partially organized, detached from Montgomery. · N.Y. Laws 1837, 60th sess., ch. 238, sec. 1/p. 227
- 1847Changed By summer of 1847, Hamilton was fully organized. · Aber and King, 51
- 1860Gained territory Hamilton gained from Fulton. · N.Y. Laws 1860, 83d sess., ch. 178/p. 298
- 1915Exchanged territory Hamilton exchanged with Essex. · N.Y. Laws 1915, 138th sess., ch. 718, secs. 1-3/p. 2364
Land and parcels
What the maps cover in Hamilton
Who publishes each layer, how good it is, and when we last checked.
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Parcels Good enough
Lot lines and tax-map numbers for 12,947 parcels from New York State Geographic Information Systems (GIS) Clearinghouse. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 25 September 2026 · checked 15 October 2026 -
Address points Official
One point per address, 8,588 in all from NYS Office of Information Technology Services (ITS), Geospatial Services / GIS Program Office (AGOL org 'ShareGIS NY', owner NYSGIS_GPO).
edited 25 September 2026 · checked 14 October 2026 -
Buildings Reference
Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026
- Official
- from the office that keeps the record
- Good enough
- a reliable statewide or national copy
- Fallback
- a guide only; check the official record
- Missing
- nothing public found yet
People and land
Hamilton by the Census
Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.
Rules and offices
Hamilton County's official site
We have found the county's site but not its offices yet; start there.
County government
- County government
The official website of Hamilton County.
See your own lot on these maps
Open Hamilton County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.
Questions
Common questions about Hamilton County
- When was Hamilton County founded?
- Hamilton County was founded in 1816, formed from Montgomery County, and named after Alexander Hamilton.
- What is the county seat of Hamilton County?
- The county seat of Hamilton County is Lake Pleasant.
- Is there an online parcel map for Hamilton County?
- Yes. New York State Geographic Information Systems (GIS) Clearinghouse publishes a parcel map of 12,947 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Hamilton County's boundary or name changed?
- Hamilton County was created in 1816 from Montgomery County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Essex County, Fulton County and Montgomery County.
- Is my lot in a flood zone?
- We do not have flood maps for Hamilton County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby