County · code 17123
Marshall CountyIllinois
Marshall County is a county in Illinois with its county seat in Lacon. The county was created on January 19, 1839, and is named after John Marshall.
- Founded1839
- County seatLacon
- Named forJohn Marshall
- Land area387 sq mi + 12 sq mi water
- Population11,742 2020 Census
- Parcels mapped13,245 checked 16 October 2026
Where it is
Marshall on the map of Illinois
Illinois has 102 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1839 from Putnam County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Marshall County was created from Putnam County on January 19, 1839. In 1843, Marshall County gained territory from La Salle County.
- 1839
- 1839Changed Legislature authorized Marshall to gain townships 29 and 30 north, range 1 east, from La Salle, dependent on local referendum that failed (no change).La Salle· Ill. Laws 1838-1839, p. 241
- 1843Gained territory Marshall gained from La Salle.from La Salle· Ill. Laws 1842-1843, pp. 93-94
Land and parcels
What the maps cover in Marshall
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 13,245 parcels from Marshall County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 2 October 2026 · checked 16 October 2026 -
Address points Missing
No public address points layer found for Marshall County yet.
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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
Marshall 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
County government
- County government
The official website of Marshall County.
See your own lot on these maps
Open Marshall 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 Marshall County
- When was Marshall County founded?
- Marshall County was founded in 1839, formed from Putnam County, and named after John Marshall.
- What is the county seat of Marshall County?
- The county seat of Marshall County is Lacon.
- Is there an online parcel map for Marshall County?
- Yes. Marshall County publishes a parcel map of 13,245 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Marshall County's boundary or name changed?
- Marshall County was created in 1839 from Putnam County. Since then the Atlas of Historical County Boundaries records 1 later change, chiefly involving La Salle County.
- Is my lot in a flood zone?
- We do not have flood maps for Marshall County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby