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County · code 36109

Tompkins CountyNew York

Tompkins County is a county in New York with its seat in Ithaca, formed in 1817.

  • Founded1817
  • County seatIthaca
  • Named forDaniel D. Tompkins
  • Land area475 sq mi + 17 sq mi water
  • Population105,740 2020 Census
  • Parcels mapped35,230 checked 15 October 2026
Open the free map Click any parcel in Tompkins County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

TiogaSchuylerChemungSenecaCayuga Ithaca Census outline · seat marked

Where it is

Tompkins 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.

Albany CountyAllegany CountyBronx CountyBroome CountyCattaraugus CountyCayuga CountyChautauqua CountyChemung CountyChenango CountyClinton CountyColumbia CountyCortland CountyDelaware CountyDutchess CountyErie CountyEssex CountyFranklin CountyFulton CountyGenesee CountyGreene CountyHamilton CountyHerkimer CountyJefferson CountyKings CountyLewis CountyLivingston CountyMadison CountyMonroe CountyMontgomery CountyNassau CountyNew York CountyNiagara CountyOneida CountyOnondaga CountyOntario CountyOrange CountyOrleans CountyOswego CountyOtsego CountyPutnam CountyQueens CountyRensselaer CountyRichmond CountyRockland CountySt. Lawrence CountySaratoga CountySchenectady CountySchoharie CountySchuyler CountySeneca CountySteuben CountySuffolk CountySullivan CountyTioga CountyUlster CountyWarren CountyWashington CountyWayne CountyWestchester CountyWyoming CountyYates CountyTompkins County Tompkins
Counties of New York · Tompkins highlighted

History

Formed in 1817 from Broome County, Cayuga County and Seneca County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Tompkins County was created on April 7, 1817, from parts of Broome, Cayuga, and Seneca counties. It was named after Daniel D. Tompkins. The county lost land to Seneca in 1819, gained land from Tioga in 1823, gained from Steuben and Yates in 1828, and lost land to the creation of Schuyler County in 1854.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1817
    Tompkins County created Tompkins created from Broome, Cayuga, and Seneca.
    from Broomefrom Cayugafrom Seneca
    · N.Y. Laws 1816, 40th sess., ch. 189, sec. 1/p. 197
  2. 1819
    Lost territory Tompkins lost to Seneca.
    to Seneca
    · N.Y. Laws 1819, 42d sess., ch. 190/p. 239
  3. 1823
    Gained territory Tompkins gained from Tioga.
    from Tioga
    · N.Y. Laws 1822, 45th sess., ch. 75, sec. 13/p. 78
  4. 1828
    Gained territory Tompkins gained from Steuben and Yates.
    from Steubenfrom Yates
    · N.Y. Rev. Stat., 3:14-15
  5. 1854
    Lost territory Tompkins lost to creation of Schuyler.
    to Schuyler
    · N.Y. Laws 1854, 77th sess., ch. 386, secs. 1-4, 6/pp. 913-915

Land and parcels

What the maps cover in Tompkins

Who publishes each layer, how good it is, and when we last checked.

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

Tompkins by the Census

Population
105,740 2020 Census count
Housing units
46,884 2020 Census count
Land area
475 square miles
Water area
17 square miles
People per sq mi
223 population ÷ land area

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

Permits

Zoning and code

County government

See your own lot on these maps

Open Tompkins 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.

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Questions

Common questions about Tompkins County

When was Tompkins County founded?
Tompkins County was founded in 1817, formed from Broome County, Cayuga County and Seneca County, and named after Daniel D. Tompkins.
What is the county seat of Tompkins County?
The county seat of Tompkins County is Ithaca.
Is there an online parcel map for Tompkins County?
Yes. A public source publishes a parcel map of 35,230 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Tompkins County's boundary or name changed?
Tompkins County was created in 1817 from Broome County, Cayuga County and Seneca County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Schuyler County, Seneca County and Steuben County.
Who issues building permits in Tompkins County?
The county's page on building permits: Pistol Permits. Inside a city or town, ask that city first.
Who issues septic and well permits in Tompkins County?
The county's page on septic systems and wells: Contact HNP.
Is my lot in a flood zone?
We do not have flood maps for Tompkins County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door