When was Monroe County founded?

Monroe County was founded in 1821, formed from Genesee County and Ontario County, and named after James Monroe.

What is the county seat of Monroe County?

The county seat of Monroe County is Rochester.

Is there an online parcel map for Monroe County?

Yes. Monroe County publishes a parcel map of 267,959 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Monroe County's boundary or name changed?

Monroe County was created in 1821 from Genesee County and Ontario County. Since then the Atlas of Historical County Boundaries records 1 later change, chiefly involving Livingston County.

Who issues building permits in Monroe 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 Monroe County?

The county's page on septic systems and wells: Contact Us.

Is my lot in a flood zone?

We do not have flood maps for Monroe County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

County · code 36055

Monroe CountyNew York

Monroe County is located in New York and has its county seat in Rochester. The county was formed in 1821.

Founded1821
County seatRochester
Named forJames Monroe
Land area657 sq mi + 710 sq mi water
Population759,443 2020 Census
Parcels mapped267,959 checked 15 October 2026

Open the free map Click any parcel in Monroe County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated 19 October 2026

Census outline · seat marked

History

Formed in 1821 from Genesee County and Ontario County

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

Monroe County was formed in 1821 from Genesee County and Ontario County, and named after James Monroe. Rochester is the county seat.

Deeds and plats from before 1821 for land now in Monroe County may have been recorded in Genesee County and Ontario County.

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

1821
Monroe County created Monroe created from Genesee and Ontario.
from Genesee from Ontario
23 February 1821 · N.Y. Laws 1820, 44th sess., ch. 57, sec. 1/p. 46
1825
Gained territory Monroe gained from Livingston.
from Livingston
4 April 1825 · N.Y. Laws 1824, 47th sess., ch. 309/p. 361

Land and parcels

What the maps cover in Monroe

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

Parcels Good enough

Lot lines and tax-map numbers for 267,959 parcels from Monroe County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 3 September 2026 · checked 15 October 2026
Address points Official

One point per address, 405,338 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

Monroe by the Census

Population

759,443 2020 Census count

Housing units

336,262 2020 Census count

Land area

657 square miles

Water area

710 square miles · 52% of the county, including large bodies of water

People per sq mi

1,156 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

Clerk of court: deeds and plats
Hours / Location / Contact
from monroecounty.gov · checked 13 October 2026

Permits

Health department: septic and well
Mental Health Home / Contact
from monroecounty.gov · checked 13 October 2026
Pistol Permitsfrom monroecounty.gov
Transportation Engineering & Permitsfrom monroecounty.gov
Septic Systemsfrom monroecounty.gov
Septic System Replacement Fundfrom monroecounty.gov

Zoning and code

Planning and zoning
Planning & Development Home / Contact
from monroecounty.gov · checked 13 October 2026

County government

County government
The official website of Monroe County.
monroecounty.gov

See your own lot on these maps

Open Monroe 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.

Open the free map no sign-in Pro early access

Questions

Common questions about Monroe County

When was Monroe County founded?: Monroe County was founded in 1821, formed from Genesee County and Ontario County, and named after James Monroe.
What is the county seat of Monroe County?: The county seat of Monroe County is Rochester.
Is there an online parcel map for Monroe County?: Yes. Monroe County publishes a parcel map of 267,959 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Monroe County's boundary or name changed?: Monroe County was created in 1821 from Genesee County and Ontario County. Since then the Atlas of Historical County Boundaries records 1 later change, chiefly involving Livingston County.
Who issues building permits in Monroe 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 Monroe County?: The county's page on septic systems and wells: Contact Us.
Is my lot in a flood zone?: We do not have flood maps for Monroe County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby