County · code 36059
Nassau CountyNew York
Nassau County is a county in New York with its seat in Mineola, formed in 1899.
- Founded1899
- County seatMineola
- Named forWilliam III of England
- Land area285 sq mi + 169 sq mi water
- Population1,395,774 2020 Census
- Parcels mapped407,645 checked 16 October 2026
Where it is
Nassau 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 1899 from Queens County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Nassau County was created from Queens in 1899 and named after William Iii of England.
- 1899Nassau County created Nassau created from Queens. · N.Y. Laws 1899, 121st sess., ch. 588, sec. 1/p. 1336
- 1945Boundary clarified Boundary between Nassau and Queens was redefined (no change).with Queensno change· N.Y. Laws 1945, 168th sess., ch. 895, secs. 1-3/pp. 2101-2106
Land and parcels
What the maps cover in Nassau
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 407,645 parcels from Nassau County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 16 October 2026 -
Address points Official
One point per address, 500,308 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
Nassau 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.
Records
- Assessor and property records
Contact Us
Zoning and code
County government
- County government
The official website of Nassau County.
See your own lot on these maps
Open Nassau 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 Nassau County
- When was Nassau County founded?
- Nassau County was founded in 1899, formed from Queens County, and named after William III of England.
- What is the county seat of Nassau County?
- The county seat of Nassau County is Mineola.
- Is there an online parcel map for Nassau County?
- Yes. Nassau County publishes a parcel map of 407,645 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Nassau County's boundary or name changed?
- Nassau County was created in 1899 from Queens County. Its boundary has been clarified one time since, with no change on the ground.
- Who issues building permits in Nassau County?
- The county's page on building permits: Building permits. Inside a city or town, ask that city first.
- Who issues septic and well permits in Nassau County?
- The county's page on septic systems and wells: Directory of Behavioral Health Treatment Services.
- Is my lot in a flood zone?
- We do not have flood maps for Nassau County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby