County · code 39003
Allen CountyOhio
Allen County is a county in Ohio with its seat in Lima, formed in 1820.
- Founded1820
- County seatLima
- Named forEthan Allen
- Land area403 sq mi + 4.3 sq mi water
- Population102,206 2020 Census
- Parcels mapped4,550 checked 15 October 2026
Where it is
Allen 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 1820 from Logan County and Shelby County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Allen County was created from Logan and Shelby counties but was not immediately organized, remaining attached to Shelby for administrative and judicial purposes. In 1828, Allen County was detached from Shelby and attached to Mercer for judicial purposes, then fully organized and detached from Mercer in 1831. The county was named after Ethan Allen.
- 1820Allen County created Allen created from Non-County Area 9 attached to Logan and Non-County Area 7 attached to Shelby; Allen not fully organized, attached to Shelby for administrative and judicial purposes. · Ohio Laws 1819, 18th assy., loc., ch. 37/pp. 90-91; Chase, 3:ch. 429/pp. 2134-2135
- 1828
- 1831Changed Allen fully organized, detached from Mercer. · Ohio Laws 1830, 29th assy., loc., p. 94; Chase, 3:ch. 470/p. 2145
- 1848Gained territory Allen gained from Mercer, Putnam, and Van Wert; lost to creation of Auglaize. · Ohio Laws 1847, 46th assy., loc., secs. 1-4, 7/pp. 128-129
Land and parcels
What the maps cover in Allen
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 4,550 parcels from Allen County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 15 October 2026 -
Address points Official
One point per address, 48,623 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
Allen 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
Allen 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 Allen County.
See your own lot on these maps
Open Allen 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 Allen County
- When was Allen County founded?
- Allen County was founded in 1820, formed from Logan County and Shelby County, and named after Ethan Allen.
- What is the county seat of Allen County?
- The county seat of Allen County is Lima.
- Is there an online parcel map for Allen County?
- Yes. Allen County publishes a parcel map of 4,550 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Allen County's boundary or name changed?
- Allen County was created in 1820 from Logan County and Shelby County. Since then the Atlas of Historical County Boundaries records 3 later changes, chiefly involving Mercer County, Auglaize County and Putnam County.
- Is my lot in a flood zone?
- We do not have flood maps for Allen County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby