County · code 39099
Mahoning CountyOhio
Mahoning County, Ohio, is located in the northeastern part of the state and has its county seat in Youngstown. The county was created in 1846.
- Founded1846
- County seatYoungstown
- Named forMahoning River, Ohio and Pennsylvania
- Land area411 sq mi + 14 sq mi water
- Population228,614 2020 Census
- Parcels mapped160,771 checked 15 October 2026
Where it is
Mahoning on the map of Ohio
Ohio has 88 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1846 from Columbiana County and Trumbull County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Mahoning County was created on March 1, 1846, from parts of Columbiana and Trumbull counties. The county is named after the Mahoning River.
- 1846Mahoning County created Mahoning created from Columbiana and Trumbull. · Ohio Laws 1845, 44th assy., loc., p. 116
Land and parcels
What the maps cover in Mahoning
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 160,771 parcels. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 10 September 2026 · checked 15 October 2026 -
Address points Official
One point per address, 110,448 in all from Ohio Geographically Referenced Information Program (OGRIP), Ohio DAS/OIT (state GIS office).
edited 24 June 2025 · checked 13 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
Mahoning 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 Mahoning County.
See your own lot on these maps
Open Mahoning 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 Mahoning County
- When was Mahoning County founded?
- Mahoning County was founded in 1846, formed from Columbiana County and Trumbull County, and named after Mahoning River, Ohio and Pennsylvania.
- What is the county seat of Mahoning County?
- The county seat of Mahoning County is Youngstown.
- Is there an online parcel map for Mahoning County?
- Yes. A public source publishes a parcel map of 160,771 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Mahoning County's boundary or name changed?
- Mahoning County was created in 1846 from Columbiana County and Trumbull County. The Atlas of Historical County Boundaries records no boundary change since.
- Who issues building permits in Mahoning County?
- The county's page on building permits: Engineers Permits. Inside a city or town, ask that city first.
- Is my lot in a flood zone?
- We do not have flood maps for Mahoning County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby