County · code 36025
Delaware CountyNew York
Delaware County is in New York and has its county seat in Delhi. It was formed on March 10, 1797, from Otsego and Ulster counties.
- Founded1797
- County seatDelhi
- Named forDelaware River
- Land area1,443 sq mi + 25 sq mi water
- Population44,308 2020 Census
- Parcels mapped43,035 checked 16 October 2026
Where it is
Delaware 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 1797 from Otsego County and Ulster County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Delaware County was formed in 1797 from Otsego County and Ulster County, and named after Delaware River. Delhi is the county seat.
Deeds and plats from before 1797 for land now in Delaware County may have been recorded in Otsego County and Ulster County.
- 1797Delaware County created Delaware created from Otsego and Ulster. · N.Y. Laws 1797, 20th sess., ch. 33/p. 39
- 1801Gained territory Delaware gained from Ulster, lost to Greene. · N.Y. Laws 1801, 24th sess., ch. 123/p. 290
- 1812Lost territory Delaware lost small area to Ulster. · N.Y. Laws 1812, 35th sess., ch. 88/p. 427
- 1817Gained territory Delaware gained from Otsego. · N.Y. Laws 1816, 40th sess., ch. 140/p. 146
- 1822
Land and parcels
What the maps cover in Delaware
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 43,035 parcels from Delaware 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, 45,320 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
Delaware 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
Delaware 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 Delaware County.
See your own lot on these maps
Open Delaware 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 Delaware County
- When was Delaware County founded?
- Delaware County was founded in 1797, formed from Otsego County and Ulster County, and named after Delaware River.
- What is the county seat of Delaware County?
- The county seat of Delaware County is Delhi.
- Is there an online parcel map for Delaware County?
- Yes. Delaware County publishes a parcel map of 43,035 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Delaware County's boundary or name changed?
- Delaware County was created in 1797 from Otsego County and Ulster County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Otsego County, Ulster County and Greene County.
- Is my lot in a flood zone?
- We do not have flood maps for Delaware County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby