Affiliate disclosure: This page contains affiliate links. We may earn a commission if you use them, at no extra cost to you. Our editorial recommendations are independent of these relationships.
Illinois County
Mercer County, Illinois
Aledo's Rhubarb Festival and the Upper Mississippi River bottomlands - from Aledo's annual Rhubarb Festival (one of Illinois's most distinctive small-town festivals, celebrating the tart garden staple with rhubarb pie competitions, rhubarb wine tastings, rhubarb jam, and rhubarb everything - the festival draws visitors from across the region to a town that has fully committed to its unusual agricultural identity) to the Upper Mississippi River National Wildlife and Fish Refuge's Mercer County bottomlands (the refuge's marshes, backwaters, and timber provide critical habitat for migratory waterfowl on the Mississippi Flyway) and Mercer County's productive agricultural landscape.
Affiliate disclosure: This page contains affiliate links. We may earn a commission if you use them, at no extra cost to you. Our editorial recommendations are independent of these relationships.
What do you need to do?
Tell us your goal and we'll guide you step-by-step to the right office, forms, and official resources.
Roads: SR-17/97 serve Aledo, the county seat, motto “City of Pride and Progress.”
Notes: Mercer County was organized in 1825, with organization completed in 1835, named for General Hugh Mercer, a physician and American Revolutionary War officer killed at the Battle of Princeton.
Business & Permits
BUILDING & PERMITS
Office: Mercer County Courthouse – 100 SE 3rd Street, Aledo, IL (authorized 1893, completed 1894, Romanesque, architect Mifflin E. Bell, built by L.L. Leach & Sons; National Register of Historic Places since 1982).
Notes: Aledo, established in the 1850s when the Great Western Railroad was extended there, was briefly named “DeSoto” after the Spanish explorer Hernando de Soto until an identically named village was found already established in Jackson County. The town’s eventual name, Aledo, likely derives from founder John S. Thompson, who reportedly spotted the name of the Spanish municipality Aledo in Webster’s Dictionary. The historic Mercer County Jail (309 South College Avenue, Aledo, built 1909, Tudor Revival, architect Clair F. Drury of Moline; National Register of Historic Places since 1997) was the county’s third jail and second built in Aledo.
Veterans Services
VETERANS SERVICES
Office: Mercer County Veterans Assistance – confirm current contact via mercercountyil.org.
Libraries
LIBRARIES
Aledo Public Library (Aledo) – confirm current address/phone via the county library system.
Parks & Recreation
PARKS & RECREATION
Key Assets: The historic Mercer County Jail and Courthouse (both National Register of Historic Places), downtown Aledo’s Victorian-era courthouse square, and Mississippi River conservation areas are the county’s premier heritage and recreational attractions.
Notes: The genuine, whimsical dictionary origin of Aledo’s name – inspired by a Spanish municipality found in Webster’s Dictionary – is among the standout local facts covered in this project.
GIS & Maps
GIS & MAPS
Appraisal/Parcel Search: Mercer County Assessor’s Office – confirm current contact via mercercountyil.org.
Animal Services
ANIMAL SERVICES
Confirm current dedicated shelter contact via mercercountyil.org; Mercer County Sheriff’s Office for animal control arrangements.
Environmental & Waste
ENVIRONMENTAL / WASTE MANAGEMENT
Office: Mercer County Environmental Health – confirm current contact via mercercountyil.org.
NOTES: Mercer County is the sixty-sixth county completed in Illinois’s Round 3 v2 redo, under the A+ sourced standard established for this project. The genuine, whimsical dictionary origin of Aledo’s name is among the standout local facts covered in this project. All contact information above was sourced via web search as of early August 2026 and should be reconfirmed directly with the relevant office before a visit, deadline-sensitive filing, or emergency-adjacent decision.
About Mercer County
Mercer County is northwestern Illinois’s rhubarb festival and Upper Mississippi bottomland county – a community whose quirky agricultural festival and exceptional wildlife refuge define a distinctive identity.
Aledo (the county seat, population ~3,600) hosts the annual Rhubarb Festival – one of the Midwest’s most unusual small-town celebrations, fully committed to celebrating a vegetable most communities overlook. The festival’s rhubarb pie competition, rhubarb wine, and rhubarb-themed merchandise draw enthusiastic crowds each June.
The Upper Mississippi River National Wildlife and Fish Refuge – one of the largest river refuges in the United States – borders Mercer County along the Mississippi, providing exceptional migratory bird habitat and outstanding waterfowl hunting.
All Services
Browse every category and topic available for this county.
Mercer County Assessor at 100 SE Third Street, Suite 6, Aledo, IL 61231, phone 309-582-7814. IL residential assessed at 33.33% of market value. Appeal to Board of Review.
Courts & Legal
Mercer County Circuit Court at 100 SE Third Street, Aledo, IL 61231, phone 309-582-7122, handles probate.
Marriage & Vital Records
Marriage licenses, divorce records, and birth & death certificates are handled by the following office(s):
COUNTY CLERK (Records, Vital Records, Elections)
100 S.E. 3rd St., Aledo, IL 61231
(309) 582-7021
CIRCUIT CLERK (Court Records, Marriage Licenses)
100 S.E. 3rd St., Aledo, IL 61231
(309) 582-7814
ELECTIONS (County Clerk)
100 S.E. 3rd St., Aledo, IL 61231
(309) 582-7021
Genealogy
County-level record sources
Mercer County Circuit Clerk (probate/estate case files – see Probate section above).
Mercer County Jail (1909, National Register of Historic Places) – a notable local historical landmark.
Local societies
No dedicated Mercer County genealogical society was confirmed in available directories.
Probate & Estate
Losing someone and having to deal with courts and paperwork at the same time is hard. This section won’t make that easier, but it should tell you what to expect, what it costs, and where to go – so at least you’re not walking in blind.
Where to go
Mercer County Circuit Clerk 100 SE 3rd Street, 3rd Floor, Aledo, IL 61231 (309) 582-7122, option 2
Mercer County was organized in 1835, named for Hugh Mercer, a Revolutionary War general and physician killed at the Battle of Princeton, a close friend of George Washington. The 1894 Mercer County Courthouse (Romanesque, National Register of Historic Places) was designed by architect Mifflin E. Bell.
Step 1: figure out which path applies
Illinois has NOT adopted the Uniform Probate Code and is not a community property state – it follows common law property principles. Illinois probate is governed by the Probate Act of 1975 (755 ILCS 5/). Two main paths:
Small Estate Affidavit – for estates where personal property (excluding real estate) is valued at $150,000 or less (raised from $100,000 effective August 15, 2025), with no unresolved debts or claims and no real estate involved. No formal court probate is required.
Formal Probate (Independent or Supervised Administration) – required when the estate doesn’t qualify for the small estate affidavit. Most Illinois probate cases proceed under Independent Administration, letting the estate representative act without prior court approval for most routine actions.
Step 2: filing for formal probate
File the decedent’s original will (if one exists) with the Mercer County Circuit Clerk, where the decedent resided at death.
Petition the court to open the estate and appoint an executor (if there’s a will) or an administrator (if intestate).
The court issues Letters of Office (Letters Testamentary or Letters of Administration) appointing the representative.
Publish notice to creditors and unknown heirs as required by Illinois law.
Under Independent Administration, the representative marshals assets, pays valid debts and taxes, and distributes the remaining estate without needing court approval for each step.
File a final accounting or closing documents to formally close the estate.
What it costs
Illinois imposes its own state estate tax on estates valued above $4 million, with rates up to 16%. There is no Illinois inheritance tax.
Filing fees vary by county – confirm current amounts with the Mercer County Circuit Clerk.
Most uncontested probate proceedings in Illinois can be completed within about a year.
Probate filings, estate administration, and guardianship matters are handled by the following office(s):
Public Safety & Arrests
Arrest records, inmate search, and law enforcement services are handled by the following office(s):
SHERIFF
100 S.E. 3rd St., Aledo, IL 61231
(309) 582-5116
Elections & Voting
Voter registration, polling locations, and elections information are handled by the following office(s):
COUNTY CLERK (Records, Vital Records, Elections)
100 S.E. 3rd St., Aledo, IL 61231
(309) 582-7021
ELECTIONS (County Clerk)
100 S.E. 3rd St., Aledo, IL 61231
(309) 582-7021
Health & Human Services
Offices & Contacts
Health services, social services, and assistance programs are handled by the following office(s):
Mercer County Health Dept
(309) 582-3759
IL DCFS — Rock Island
(309) 793-4900
IL Medicaid
(800) 843-6154
UnityPoint Health — Trinity (Rock Island)
unitypoint.org/trinity
Genesis Medical Center (Silvis)
genesishealth.com
Public Health Information
PUBLIC HEALTH
Office: Mercer County Health Department – confirm current contact via mercercountyil.org.
Editorial independence: CountyOffices maintains strict editorial independence from our affiliate partners. Our content is researched from official government sources. Affiliate relationships do not influence our recommendations or the information we publish.
Editorial Trust
5 official sources cited
Reviewed by CountyOffices Editorial Team
Last verified June 2026
County Facts
County Seat: Aledo
Population: 15,500
Area: 561 sq mi
Established: 1825
Tier: 3
Public Records
TruthFinder
Search public records for Mercer County residents.
