Illinois Counties Map

Illinois, known as the “Land of Lincoln,” boasts an incredible mix of rural landscapes, bustling cities, rich history, and diverse cultures. Situated in the Midwestern United States, Illinois is partitioned into 102 counties.

The counties of Illinois are remarkably varied in terms of geography, economy, and population. In this exploration, we’ll delve into an Illinois Counties Map that illuminates the largest cities within each county and the respective boundaries. We’ll also take a closer look at what distinguishes some of Illinois’ standout counties.

Illinois (IL) on the US Map

The State of Illinois highlighted on the US map.
The state of Illinois highlighted on the US map.

Map of Illinois Counties

Below is a map of the 102 counties of Illinois (you can click on the map to enlarge it and to see the major city in each county).

A map showing the counties of Illinois with surrounding state names and Lake Michigan labeled.
Illinois Counties Map with cities.

Click on any of the counties on the map to see its population, economic data, time zone, and zip code (the data will appear below the map). Data is sourced from the US Census 2021.

List of the Counties of Illinois:

CountyPopulationPer sq. kmLargest City
Adams County65,87829.74Quincy
Alexander County5,4889Cairo
Bond County16,80417.06Greenville
Boone County53,59273.71Belvidere
Brown County6,3307.99Mount Sterling
Bureau County33,33814.81Peru
Calhoun County4,5376.9Hardin
Carroll County15,58613.51Savanna
Cass County13,05813.42Beardstown
Champaign County206,58380.07Champaign
Christian County34,03818.52Taylorville
Clark County15,58712Marshall
Clay County13,31310.98Flora
Clinton County37,04830.18Centralia
Coles County47,54236.11Charleston
Cook County5,265,3982151.47Chicago
Crawford County18,82516.38Robinson
Cumberland County10,52811.75Casey
De Witt County15,65315.2Clinton
DeKalb County100,92261.72DeKalb
Douglas County19,70818.26Tuscola
DuPage County934,0941100.23Chicago
Edgar County16,99810.53Paris
Edwards County6,23310.82Albion
Effingham County34,57627.88Effingham
Fayette County21,51411.59Vandalia
Ford County13,58910.8Paxton
Franklin County38,06835.94West Frankfort
Fulton County34,02215.17Canton
Gallatin County5,0386.02Shawneetown
Greene County12,1878.66Carrollton
Grundy County52,36448.35Morris
Hamilton County8,0217.13McLeansboro
Hancock County17,7508.63Hamilton
Hardin County3,7008.05Rosiclare
Henderson County6,4856.61Oquawka
Henry County49,41223.18Kewanee
Iroquois County27,3629.45Watseka
Jackson County53,67635.51Carbondale
Jasper County9,3247.28Newton
Jefferson County37,36225.25Mount Vernon
Jersey County21,53322.5Jerseyville
Jo Daviess County21,99514.13Galena
Johnson County13,23814.87Vienna
Kane County518,648385.57Aurora
Kankakee County108,10461.7Kankakee
Kendall County130,757157.65Aurora
Knox County50,19327.05Galesburg
Lake County714,484621.85Round Lake Beach
LaSalle County109,98637.41Ottawa
Lawrence County15,46516.04Lawrenceville
Lee County34,37318.31Dixon
Livingston County35,90213.28Streator
Logan County28,23817.64Lincoln
Macon County104,33169.38Decatur
Macoupin County45,15220.2Carlinville
Madison County266,112143.6Alton
Marion County37,78125.48Centralia
Marshall County11,78111.76Henry
Mason County13,2259.47Havana
Massac County14,28023.25Metropolis
McDonough County27,74318.18Macomb
McHenry County310,749198.84Crystal Lake
McLean County171,45555.95Bloomington
Menard County12,34315.16Petersburg
Mercer County15,77910.86Aledo
Monroe County34,73234.8Columbia
Montgomery County28,48215.63Litchfield
Morgan County33,18922.52Jacksonville
Moultrie County14,63416.82Sullivan
Ogle County51,78726.36Rockford
Peoria County182,439113.85Peoria
Perry County21,15818.49Du Quoin
Piatt County16,66414.65Monticello
Pike County14,9236.93Pittsfield
Pope County3,8204Golconda
Pulaski County5,27910.23Mounds
Putnam County5,63813.6Granville
Randolph County30,63220.56Chester
Richland County15,87617.03Olney
Rock Island County144,694130.68Moline
Saline County23,86924.25Harrisburg
Sangamon County196,75987.5Springfield
Schuyler County6,9536.14Rushville
Scott County4,9237.58Winchester
Shelby County21,16010.77Pana
St. Clair County258,597151.8Belleville
Stark County5,4367.29Wyoming
Stephenson County44,81730.67Freeport
Tazewell County131,97778.82Pekin
Union County17,25916.12Anna
Vermilion County74,95332.22Danville
Wabash County11,41419.73Mount Carmel
Warren County16,88712.02Monmouth
Washington County13,8279.49Centralia
Wayne County16,2508.79Fairfield
White County13,95910.89Carmi
Whiteside County55,93231.57Sterling
Will County696,403321.68Aurora
Williamson County67,27161.81Marion
Winnebago County285,471214.83Rockford
Woodford County38,57128.23Eureka

Largest Counties in Illinois by Population

Cook County

An aerial view of the Chicago skyline bordering Lake Michigan.
Chicago, Illinois

Cook County is the most populous county in Illinois and an epicenter of culture, commerce, and history. Established in 1831, it was named after Daniel Cook, one of the earliest advocates for Illinois statehood. It is located in the northeastern part of the state, bordering Lake Michigan and Indiana.

Chicago, the county seat and the third-largest city in the US, offers a mix of architectural wonders, arts, global cuisines, and a distinctive music scene. The city is home to landmarks like Willis Tower, Wrigley Field, and the Cloud Gate sculpture, all of which can be seen through many guided tours of Chicago.

Beyond Chicago’s urban expanse, Cook County has a plethora of parks and forest preserves. These green spaces provide residents and visitors with opportunities for outdoor activities such as hiking, cycling, and picnicking. The Forest Preserves of Cook is one of the oldest and largest forest preserve districts in the US.

Educational institutions, like the University of Chicago and Northwestern University, along with numerous cultural establishments, make Cook County an educational and cultural powerhouse. It’s also connected to the Atlantic Ocean, despite its inland location, thanks to its access to Lake Michigan and the St. Lawrence Seaway

DuPage County

A view of the DuPage County Administration Building sitting next to water.
DuPage County Administration Building

DuPage County, also located in northeastern Illinois, stands as another heavily populated and significant hub in the state. Founded in 1839, it was named after the DuPage River, which meanders through several of its communities. With Wheaton as its county seat, DuPage boasts a blend of urban sophistication and suburban charm.

Located adjacent to Cook County, DuPage is an economically important hub, as it houses numerous corporate headquarters, leading businesses, and educational institutions. Among these, the College of DuPage is noteworthy for its contribution to higher education and workforce development in the region.

In addition to its commercial attributes, DuPage County places a strong emphasis on green spaces and recreation. It offers residents and visitors an array of parks, trails, and nature preserves, emphasizing the region’s commitment to environmental stewardship. The Forest Preserve District of DuPage County offers great hiking and picnicking options. 

The county’s infrastructure is well-developed, with an efficient transportation network that includes major highways and transit systems, facilitating seamless connectivity within and beyond its borders.

Lake County

A view of a lake at the Independence Grove Forest Preserve in Lake County, Illinois.
Independence Grove in Libertyville, Illinois

Lake County, nestled in the northeasternmost corner of Illinois, is unique for its natural beauty, historical significance, and economic impact. It’s also the third-most populous county in the state. Established in 1839, its identity is intrinsically linked to Lake Michigan, which forms its eastern boundary, influencing both its geography and its cultural evolution.

One of Lake County’s defining features is its commitment to preserving the environment. The Lake County Forest Preserves encompass thousands of acres, providing habitats for diverse flora and fauna, recreational opportunities for residents, and a tangible connection to the region’s natural history. 

Popular preserves such as Independence Grove in Libertyville and Ryerson Woods in Riverwoods showcase the county’s dedication to environmental stewardship and offer avenues for hiking, bird-watching, and educational programs. The land covered by the forest preserves is the traditional homeland of the Ojibwe, Odawa, and Potawatomi nations.

Lake County is also an education hub. Institutions like the College of Lake County provide critical resources for skill development, research, and community outreach. Educational institutions are just one part of the multifaceted economic landscape in Lake County. 

Once known primarily for its manufacturing legacy, the county has seen a discernible shift towards services, technology, and healthcare. Companies have recognized the advantages of setting up in Lake County, given its strategic location near Chicago, and GDP has risen accordingly.

Will County

A street-level view of downtown Joliet, Illinois on a clear day. 
Downtown Joliet, Illinois

Will County, situated in northeastern Illinois, is also among the most populous counties in the state. Established in 1836, it was named in tribute to Dr. Conrad Will, a respected statesman and physician of the region. 

Joliet, the county seat, shines as a centerpiece of Will County’s architectural and cultural landscape, showcasing a variety of historical landmarks such as the Old Joliet Prison and the Joliet Iron Works Historic Site. Joliet is the third-largest city in Illinois.

Throughout its expanse, Will County’s landscape includes elements that are both urban and pastoral. The Des Plaines River meanders through the county, providing a focal point for recreational activities such as fishing and hiking. 

Will County’s commitment to environmental preservation is evident in its numerous parks and nature reserves. The Midewin National Tallgrass Prairie, as an example, stands as a beacon of conservation efforts. Spanning thousands of acres, this pristine prairie offers a haven for flora, fauna, and those seeking a natural retreat with its 33 miles (53 km) of trails.

Economically, while traditional sectors like agriculture remain vital, the technology, logistics, and healthcare industries have gained importance. This shift has been facilitated by the county’s strategic location and excellent transport links

Kane County

Wild geese walk toward a lake in Kane County’s Fabyan Forest Preserve.
Fabyan Forest Preserve in Kane County, Illinois

The fifth-most populous county in Illinois is Kane County, with a population exceeding 500,000. It’s located in northern Illinois and was established in 1836 from parts of LaSalle County. The name of the county comes from Elias Kent Kane, the first US Senator of Illinois.

Geneva, a city that lies along the picturesque Fox River, is designated as the county seat, and Aurora is the largest city in the county. The Fox River Valley is one of the most striking features of Kane County and is responsible for attracting tourists to Geneva. The river was also once an important trade route.

There are other natural attractions in addition to the Fox River as well. Kane County’s Fabyan Forest Preserve offers a blend of nature trails, historical sites, and a renowned Japanese Garden. Similarly, the Tekakwitha Woods Forest Preserve provides an immersive environment for visitors to learn about local ecology and conservation efforts.

A sense of community is maintained in Kane County through its educational institutions and through annual events. Elgin Community College and Aurora University are among the several institutions that cater to the academic needs of residents, and events like the annual Kane County Fair in St. Charles highlight the county’s agricultural roots.

Smallest Counties in Illinois by Population

Hardin County

A street-level view of an empty Main Street in Elizabethtown, Illinois.
Main Street in Elizabethtown, Illinois

Hardin County, positioned in the southeastern corner of Illinois, has the smallest population of any county in the state. Established in 1839, the county was named after Hardin County in Kentucky, which was named in honor of Colonel John Hardin, an early pioneer.

One of the county’s most striking features is its proximity to the Ohio River. This majestic river, which forms the county’s eastern boundary, has played a pivotal role in its history, both as a transportation route and as a source of livelihood. Today, the river continues to be a focal point for recreation, including fishing and boating at sites such as Cave-in-Rock State Park.

A significant highlight of Hardin County is the Shawnee National Forest. This sprawling natural sanctuary offers a haven for wildlife and is a popular destination for hiking, camping, and horseback riding. The forest’s Garden of the Gods, with its impressive rock formations, draws visitors from far and wide, making it a must-visit spot in the region.

The county seat of Hardin County, Elizabethtown, has a population of less than 500 people; the largest city in the county is Rosiclare, which was once known as the “Fluorite Capital of the World.”

Pope County

A view of a street lined with buildings in Golconda, Illinois.
Golconda, Illinois 

The second-least populous county in Illinois is Pope County, located in the southern part of the state. It was created in 1816 and named in honor of Nathaniel Pope, a distinguished figure in the early days of Illinois Territory.

The Ohio River forms a part of Pope County’s eastern boundary, offering both picturesque views and a location for outdoor recreation. The waterway has played a crucial role in shaping the county’s history and continues to influence its culture and economy.

Golconda, the county seat, is the heart of Pope County and its largest city. It was named after Golconda Fort in India and was part of the Trail of Tears that thousands of Native Americans were forced to walk between 1838 and 1839.

A significant portion of the Shawnee National Forest and its parks lies within Pope County. This vast natural reserve provides a haven for wildlife, hiking trails, camping spots, and some of the region’s unique geological attractions. Dixon Springs State Park is an excellent choice for birdwatching.

Calhoun County

A view of the green Joe Page Bridge extending over the Illinois River.
The Joe Page Bridge in Hardin, Illinois

Calhoun County, situated in the southwestern part of Illinois, offers a unique landscape characterized by its strategic location between the Mississippi and Illinois Rivers. Formed in 1825, the county was named after John C. Calhoun, the seventh Vice President of the United States. 

Known for its natural beauty and abundant waterways, Calhoun County presents a compelling attraction for those interested in outdoor recreational activities such as fishing, boating, and hiking. It’s also possible to camp at the McCully Heritage Project, located near Kampsville, Illinois.

The county seat and largest population center is Hardin, an inviting town that offers essential amenities and services to both residents and visitors. It serves as the administrative and social focal point for the broader community, offering public services, educational facilities, and community events.

Notable Illinois Counties

Champaign County

A creek flows between university buildings and grass.
Boneyard Creek and buildings on the University of Illinois Urbana-Champaign campus

Another notable county in Illinois is Champaign County, situated in the east-central part of the state. Founded in 1833, the county was named after Champaign County in Ohio. Urbana serves as the county seat and, along with Champaign, forms the Champaign-Urbana Metropolitan Area, often referred to as the “twin cities.”

One of the most defining features of Champaign County is the presence of the University of Illinois Urbana-Champaign. This prestigious institution has a significant impact on the county’s cultural, economic, and social landscape. It not only provides high-quality education but also creates job opportunities, technological advancements, and avenues for cultural enrichment.

The Research Park at the University of Illinois is a hub for innovation and entrepreneurship, fostering collaborations between students, researchers, and corporations. Beyond the education sector, Champaign County has strong economic performers in the manufacturing, agricultural technology, and medical technology industries.

Champaign County also offers a wide range of recreational and cultural activities. From beautiful parks to music venues and art galleries such as the Gilbert Gallery, the county provides an enriching environment for its residents and visitors alike. 

Madison County

A view of the corner of the City Hall building in Edwardsville, Illinois.
Edwardsville, Illinois City Hall

Madison County is located in the southwestern part of Illinois and is part of the St. Louis Metropolitan Area. Established in 1812, the county was named after James Madison, the fourth President of the United States. Edwardsville serves as the county seat and is one of the oldest cities in the state. 

Economically, Madison County is diverse and robust. It boasts a mix of industries including manufacturing, healthcare, logistics, and services.

The county benefits from its proximity to St. Louis, Missouri, which provides additional opportunities for business collaborations and employment. There are also a variety of economic development programs in place to attract businesses.

Education is a priority in Madison County, which hosts a variety of public and private schools offering high-quality education. The county is also home to Southern Illinois University Edwardsville (SIUE), which provides a range of undergraduate and graduate programs and contributes to the local economy.

The county also offers numerous recreational and cultural opportunities. Areas around the Mississippi River and the Chain of Rocks Bridge provide scenic beauty and recreational options like boating, fishing, and hiking. Additionally, Madison County has several parks, museums, and historical sites to enjoy.

Sangamon County

A statue of Abraham Lincoln stands in front of the Illinois State Capitol.
Illinois State Capitol in Springfield

Sangamon County, located in central Illinois, is perhaps most renowned as the home of Springfield, the state capital. Established in 1821, the county has played a pivotal role in American and Illinois history. 

Springfield is famously linked with Abraham Lincoln, the 16th President of the United States, who lived there for over two decades. The Abraham Lincoln Presidential Library and Museum, along with Lincoln’s home and his final resting place at Oak Ridge Cemetery, are major tourist attractions that underscore the county’s historical significance.

The county also serves as a critical center for state government and is a key hub for healthcare and education. Institutions like Southern Illinois University School of Medicine contribute to a robust healthcare system, making the county a healthcare destination in the region. 

In terms of natural beauty, Sangamon County features parks and recreational areas such as the Lincoln Memorial Garden and the Washington Park Botanical Garden, providing residents and visitors opportunities for outdoor activities. 

More About Illinois Counties: FAQs

What is the oldest county in Illinois?

St. Clair County, formed in 1790, is the oldest county in Illinois.

Are there any counties in Illinois known for their natural beauty?

Yes, counties like Jo Daviess in the northwest corner of the state are known for their scenic beauty. Jo Daviess County occupies the banks of the Mississippi River and is known for its picturesque, rolling hills.

What is the largest county in Illinois?

The largest county by total area in Illinois is McLean County, which covers an area of 1,186 square miles (3,070 km2).

Which Illinois county is the smallest?

Putnam County is the smallest by total area in Illinois. It covers an area of just 172 square miles (450 km2).

Image Sources and Copyright Information
  • Aerial View of Chicago Skyline at Sunrise: © marchello74/Shutterstock
  • Modern Government Building by the Lake with Reflective Windows and Landscaped Surroundings: © Henryk Sadura/Shutterstock
  • Tranquil Lake with Sky Reflection Surrounded by Lush Greenery: © Sarah Quintans/Shutterstock
  • Sunny Day on a Historic Downtown Street in Joliet, Illinois: © Nejdet Duzen/Shutterstock
  • Geese by the Lake at Fabyan Forest Preserve in Kane County, Illinois on a Sunny Autumn Day: © Nejdet Duzen/Shutterstock
  • Sunny Day on a Historic Small Town Street in Elizabethtown, Illinois: © Roberto Galan/Shutterstock
  • Sunny Day on a Small Town Main Street: © Roberto Galan/Shutterstock
  • Joe Page Bridge, a Strauss Vertical Lift Bridge in Calhoun County: © Iavor/Shutterstock
  • Scenic View of Boneyard Creek with Geese and Historic Buildings in Urbana, Illinois: © Ken Wolter/Shutterstock
  • Early Morning Light Casting Shadows on a Street Corner Building: © RozenskiP/Shutterstock
  • Statue of Abraham Lincoln in Front of the Illinois State Capitol Building: © Paul Brady Photography/Shutterstock