County · code 36083
Rensselaer CountyNew York
Rensselaer County is in New York and has Troy as its county seat. It was formed on February 7, 1791, and named after Kiliaen van Rensselaer.
- Founded1791
- County seatTroy
- Named forKiliaen van Rensselaer
- Land area652 sq mi + 13 sq mi water
- Population161,130 2020 Census
- Parcels mapped64,346 checked 15 October 2026
Where it is
Rensselaer 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 1791 from Albany County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Rensselaer County was created from Albany on February 7, 1791. In 1822, it gained a small area from Washington County. In 1888, it lost Havre Island to Saratoga County.
- 1791Rensselaer County created Rensselaer created from Albany. · N.Y. Laws 1791, 14th sess., ch. 4/p. 201
- 1822Gained territory Rensselaer gained small area from Washington. · N.Y. Laws 1822, 45th sess., ch. 116/p. 116
- 1888Lost territory Rensselaer lost Havre Island to Saratoga. · N.Y. Laws 1888, 111th sess., ch. 42/p. 85
Land and parcels
What the maps cover in Rensselaer
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 64,346 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, 85,246 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
Rensselaer 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
Who to ask before you build, dig or sell
Official county pages only. We link to them; we do not copy them, because they change.
Inside a city or town, permits usually come from that city rather than the county.
Zoning and code
GIS and maps
County government
- County government
The official website of Rensselaer County.
See your own lot on these maps
Open Rensselaer 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 Rensselaer County
- When was Rensselaer County founded?
- Rensselaer County was founded in 1791, formed from Albany County, and named after Kiliaen van Rensselaer.
- What is the county seat of Rensselaer County?
- The county seat of Rensselaer County is Troy.
- Is there an online parcel map for Rensselaer County?
- Yes. New York State Geographic Information Systems (GIS) Clearinghouse publishes a parcel map of 64,346 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Rensselaer County's boundary or name changed?
- Rensselaer County was created in 1791 from Albany County. Since then the Atlas of Historical County Boundaries records 2 later changes, most of them small boundary adjustments, chiefly involving Saratoga County and Washington County.
- Who issues building permits in Rensselaer County?
- The county's page on building permits: Pistol Permit Information. Inside a city or town, ask that city first.
- Who issues septic and well permits in Rensselaer County?
- The county's page on septic systems and wells: Health department: septic and well.
- Is my lot in a flood zone?
- We do not have flood maps for Rensselaer County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby