Blog · October 13, 2026 · Illinois
Using the Mercer County Plat Book
The free official plat book for Mercer County, how to search it, and what the parcel data does and doesn't tell you about owners, acreage and property lines.
Main page: Mercer County, IL GIS & Parcel Viewer (official map link, Mercer County facts and neighboring maps).
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The Mercer County plat book is a public tool, and for anyone shopping, building or hunting near Joy, it's the fastest way to put an owner's name on a piece of ground.
You'll find the viewer link, notes on Joy and the land around it, and short answers to common questions about property lines and land records.
Where to open the official Mercer County plat book
For parcels from Aledo to Millersburg, the Sidwell Portico is the county's own public map. A disclaimer pops up on the first visit. Click through it to reach the map. The quickest search in Mercer County is usually the parcel number from a tax bill; owner and address searches work too. Bookmark the Platbookmapper page for Mercer County too; we update it when the official map moves.
Where to find a Mercer County plat book in Illinois
A plat book is the paper cousin of the online parcel map: a township-by-township atlas with owner names, handy in a truck near Keithsburg. Ownership around Keithsburg changes every year, so the online map is the better check on who owns a tract today.
Who's clicking on Mercer County parcels
The same map serves very different jobs around Joy.
- A buyer who wants ten or twenty acres near Aledo can rule out most of the wrong tracts from a desk before driving out.
- Vacant-lot hunters working the edges of Aledo look for parcels with no structures and owners who live out of the area.
- A hunter driving the back roads near Millersburg can match a promising woodlot to an owner name in seconds.
Mercer County at a glance: towns and land
Aledo is the county seat, and other towns on the map include Keithsburg, New Boston, Alexis, and Joy. Mercer County was created in 1825 and takes its name from Hugh Mercer. Roughly 15,487 people (Census Bureau, 2023) share Mercer County's 561 square miles of land. At that density most of the Mercer County map is farm and wooded ground, with smaller lots clustered around Joy and along paved roads.
The Mercer County economy in brief
Mercer County had 269 business establishments in 2022 (County Business Patterns), led by other services, construction, and retail trade. What stands out is utilities, fabricated metal product manufacturing, and wholesale of nondurable goods (including farm products): those sectors make up a much larger slice of local businesses than they do nationally. Freight and farm businesses depend on road access, so frontage is worth checking on any tract near North Henderson. That context helps when you read the parcel pattern around Alexis: jobs and land use move together.
How accurate are Mercer County, IL property lines?
A lot line on the Mercer County plat book near Joy is a drawing based on deeds, not a measurement taken on site. The section grid shapes many farm tracts around Millersburg; boundaries often follow quarter-section lines you can spot on the map. For walking the corners yourself, our guide to finding property corners helps; for a legal answer, call an Illinois licensed surveyor.
Acreage and vacant lot search
Five steps for vacant land in Mercer County:
- With imagery on, zoom to the edge of North Henderson where subdivisions give way to open ground.
- A tax bill mailed far from Millersburg usually means an absentee owner, so note the mailing address on each record.
- Size up price by comparing a few similar tracts around North Henderson on the assessment records.
- Confirm legal access. In Mercer County, as anywhere, a parcel with no road frontage depends on an easement.
- Before you sign for land near New Boston, check what the local planning and health offices will allow on it.
Where Mercer County deeds and plats are kept
For land near Keithsburg, the parcel record is the index; the recorded deed is the source. Which office that is depends on how Illinois organizes it, so look it up on the Mercer County government site before you call. For subdivision lots in Keithsburg, the plat book and page on the record leads straight to the recorded plat.
Near the county line
A farm that runs from Mercer County into Henry County will have separate parcel records on each side; the other neighbors are Henderson County, Knox County, Rock Island County, and Warren County. All of them are listed on our Illinois page.
Quick answers
Can I check flood zones on the Mercer County map?
Look in the layer list of the Sidwell Portico. If there's no flood layer, FEMA's flood map service covers Mercer County.
Can hunters use the Mercer County, Illinois parcel map to find landowners?
Use it to find the owner of a woodlot near North Henderson, then ask; the map itself grants no hunting rights.
How can I tell who owns land near Joy?
Look up the address in North Henderson, or click the tract. Owner names on the Mercer County map come from recorded deeds.
Is there a printed plat book for Mercer County, Illinois?
Whether a current printed edition exists for Mercer County varies; the free online map covering Joy and the rest of the county is the dependable option.
Where do property lines run on a Mercer County, IL lot?
For a lot in North Henderson, start with the parcel map, then get the recorded plat; a surveyor sets the exact corners.
Open the official Mercer County, IL parcel map Mercer County in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey, especially for fences, setbacks, or boundary disputes.