Illinois State Maps
These maps show Illinois Counties, Cities, Federal Areas, Physiographic, and Ecoregions.

The Counties of Illinois and Their Name Origins
- Adams County: Named for John Adams, the second President of the United States.
- Alexander County: Named for William M. Alexander, an early settler and state legislator.
- Bond County: Named for Shadrach Bond, the first Governor of Illinois.
- Boone County: Named for Daniel Boone, the famous American frontiersman.
- Brown County: Named after U.S. General Jacob Brown, a hero of the War of 1812.
- Bureau County: Named for Michel Aco, a trader who built a trading post on Bureau Creek.
- Calhoun County: Named for John C. Calhoun, the seventh Vice President of the United States.
- Carroll County: Named after Charles Carroll, a signer of the Declaration of Independence.
- Cass County: Named for Lewis Cass, a U.S. Senator and presidential candidate.
- Champaign County: Named after Champaign County, Ohio.
- Christian County: Originally called Dane County, it was renamed in 1839 for Christian County, Kentucky.
- Clark County: Named for George Rogers Clark, an American Revolutionary War hero.
- Clay County: Named for Henry Clay, a U.S. Senator and Secretary of State.
- Clinton County: Named for DeWitt Clinton, Governor of New York and advocate of the Erie Canal.
- Coles County: Named after Edward Coles, the second Governor of Illinois.
- Cook County: Named after Daniel P. Cook, an early Illinois statesman and Congressman.
- Crawford County: Named for William H. Crawford, U.S. Secretary of the Treasury and presidential candidate.
- Cumberland County: Named for the Revolutionary War hero the Marquis de Lafayette, who was also known as the "Hero of the Cumberland."
- DeKalb County: Named for Johann De Kalb, a German soldier who served as a major general in the Continental Army.
- DeWitt County: Named for DeWitt Clinton, Governor of New York.
- Douglas County: Named after Stephen A. Douglas, U.S. Senator from Illinois and presidential candidate.
- DuPage County: Named for the DuPage River, which flows through the area.
- Edgar County: Named after John Edgar, an early settler and local leader.
- Edwards County: Named for Ninian Edwards, the third Governor of Illinois.
- Effingham County: Named after Lord Effingham, who opposed British policies before the American Revolution.
- Fayette County: Named for the Marquis de Lafayette, a French hero of the American Revolutionary War.
- Ford County: Named for Thomas Ford, the eighth Governor of Illinois.
- Franklin County: Named for Benjamin Franklin, one of the Founding Fathers of the United States.
- Fulton County: Named for Robert Fulton, the inventor of the steamboat.
- Gallatin County: Named for Albert Gallatin, U.S. Secretary of the Treasury.
- Greene County: Named for Nathanael Greene, a general in the American Revolutionary War.
- Grundy County: Named for Felix Grundy, a U.S. Senator from Tennessee.
- Hamilton County: Named for Alexander Hamilton, the first U.S. Secretary of the Treasury.
- Hancock County: Named for John Hancock, a leader of the American Revolution and first signer of the Declaration of Independence.
- Hardin County: Named for John Hardin, an American soldier killed by Native Americans in 1792.
- Henderson County: Named for Richard Henderson, a North Carolina judge and land speculator.
- Henry County: Named after Patrick Henry, a leader of the American Revolution.
- Iroquois County: Named for the Iroquois Confederation of Native American tribes.
- Jackson County: Named after Andrew Jackson, the seventh President of the United States.
- Jasper County: Named for Sergeant William Jasper, a hero of the American Revolution.
- Jefferson County: Named for Thomas Jefferson, the third President of the United States.
- Jersey County: Named after the state of New Jersey.
- Jo Daviess County: Named after Joseph Hamilton Daviess, a U.S. attorney and soldier killed at the Battle of Tippecanoe.
- Johnson County: Named for Richard Mentor Johnson, Vice President of the United States under Martin Van Buren.
- Kane County: Named after Elias Kane, the first Secretary of State of Illinois.
- Kankakee County: Named for the Kankakee River, which flows through the county.
- Kendall County: Named after Amos Kendall, U.S. Postmaster General under Andrew Jackson.
- Knox County: Named after Henry Knox, the first U.S. Secretary of War.
- Lake County: Named for its proximity to Lake Michigan.
- LaSalle County: Named for the French explorer René-Robert Cavelier, Sieur de La Salle.
- Lawrence County: Named after Captain James Lawrence, a naval officer in the War of 1812.
- Lee County: Named for Richard Henry Lee, a leader of the American Revolution.
- Livingston County: Named for Edward Livingston, a U.S. Secretary of State and diplomat.
- Logan County: Named for John A. Logan, a Union general in the Civil War and an Illinois politician.
- Macon County: Named for Nathaniel Macon, a U.S. Congressman and Senator from North Carolina.
- Macoupin County: Named after Macoupin Creek, a local waterway.
- Madison County: Named for James Madison, the fourth President of the United States.
- Marion County: Named after Francis Marion, a Revolutionary War hero known as the "Swamp Fox."
- Marshall County: Named for John Marshall, the fourth Chief Justice of the United States.
- Mason County: Named for George Mason, a Virginia statesman and delegate to the U.S. Constitutional Convention.
- Massac County: Named for Fort Massac, a fort established by the French in the 18th century.
- McDonough County: Named for Commodore Thomas Macdonough, a hero of the War of 1812.
- McHenry County: Named after Major William McHenry, an Indian fighter and early Illinois settler.
- McLean County: Named for John McLean, a U.S. Senator from Illinois.
- Menard County: Named after Pierre Menard, the first Lieutenant Governor of Illinois.
- Mercer County: Named for Hugh Mercer, a general in the American Revolutionary War.
- Monroe County: Named for James Monroe, the fifth President of the United States.
- Montgomery County: Named for Richard Montgomery, a general killed in the Revolutionary War.
- Morgan County: Named after General Daniel Morgan, a hero of the American Revolution.
- Moultrie County: Named after William Moultrie, a general in the American Revolutionary War.
- Ogle County: Named for Joseph Ogle, a pioneer settler in Illinois.
- Peoria County: Named after the Peoria Native American tribe.
- Perry County: Named for Commodore Oliver Hazard Perry, a hero of the War of 1812.
- Pike County: Named for Zebulon Pike, the explorer after whom Pikes Peak in Colorado is named.
- Pope County: Named for Nathaniel Pope, a U.S. Congressman and territorial judge in Illinois.
- Pulaski County: Named for Casimir Pulaski, a Polish general who fought in the American Revolution.
- Putnam County: Named after Israel Putnam, a general in the American Revolutionary War.
- Randolph County: Named for Edmund Randolph, the first U.S. Attorney General and Secretary of State.
- Richland County: Named for its rich soil and fertile land.
- Rock Island County: Named for the large island in the Mississippi River known as Rock Island.
- Saline County: Named for the saline springs in the area that were once used to produce salt.
- Sangamon County: Named after the Sangamon River, a Native American word meaning "land of plenty."
- Schuyler County: Named for Philip Schuyler, a general in the American Revolutionary War.
- Scott County: Named for Scott County, Kentucky, or possibly for General Winfield Scott, a U.S. Army officer.
- Shelby County: Named for Isaac Shelby, a Revolutionary War hero and the first Governor of Kentucky.
- St. Clair County: Named for Arthur St. Clair, the first Governor of the Northwest Territory.
- Stark County: Named for John Stark, a general in the American Revolutionary War.
- Stephenson County: Named for Benjamin Stephenson, a delegate to the U.S. Congress from the Illinois Territory.
- Tazewell County: Named for Littleton Waller Tazewell, a U.S. Senator from Virginia and Governor of Virginia.
- Union County: Named to commemorate the federal Union of the United States.
- Vermilion County: Named for the Vermilion River, which runs through the county.
- Wabash County: Named for the Wabash River, which forms the county's eastern border.
- Warren County: Named for Joseph Warren, a hero of the American Revolutionary War.
- Washington County: Named for George Washington, the first President of the United States.
- Wayne County: Named for General Anthony Wayne, a hero of the American Revolutionary War.
- White County: Named for Isaac White, a soldier killed at the Battle of Tippecanoe.
- Whiteside County: Named for Samuel Whiteside, a general in the Black Hawk War.
- Will County: Named for Dr. Conrad Will, a pioneer physician and Illinois state legislator.
- Williamson County: Named for Hugh Williamson, a signer of the U.S. Constitution from North Carolina.
- Winnebago County: Named after the Winnebago Native American tribe.
- Woodford County: Named after Woodford County, Kentucky, where many early settlers of the county came from.

Illinois State County Sizes Map
Smallest County in Illinois
Putnam County: 170 sq miles
Largest County in Illinois
McLean County: 1,185 sq miles
Mean and Median Area of Counties in Illinois
Mean Area: 600 sq miles
Median Area: 517 sq miles

Major Cities of Illinois State and Their Locations
In Illinois, major cities are typically located near key transportation routes such as rivers, railroads, and highways. Below are examples of these cities:
1. River Ports
Chicago: Located on the southwestern shores of Lake Michigan, Chicago has historically been a major hub for transportation and trade. The city's port connects the Great Lakes to the Mississippi River system, making it a key city for shipping and commerce in the Midwest.
Peoria: Situated along the Illinois River, Peoria developed as a key industrial and agricultural hub due to its river access. It remains an important center for manufacturing and is also known for its contributions to the agricultural machinery industry.
East St. Louis: Located on the eastern side of the Mississippi River, across from St. Louis, Missouri, East St. Louis historically served as a key river port and industrial city. Its location on the Mississippi River facilitated trade and transportation in the region.
Quincy: Another river city on the banks of the Mississippi River, Quincy has long been an important agricultural trading hub. Its access to river transportation made it a center for shipping agricultural products like grain and livestock.
2. Rail and Road Hubs
Springfield: The state capital, located in central Illinois, grew around its strategic position at the crossroads of major railroads. Today, Springfield is known not only for its political significance but also for its rich historical ties to Abraham Lincoln.
Rockford: Located near the Wisconsin border, Rockford became a key manufacturing center due to its proximity to rail and road networks. The city continues to play a significant role in Illinois' industrial sector, particularly in aerospace and manufacturing.
Joliet: Situated southwest of Chicago, Joliet is a major transportation hub, with key railroads, highways, and the Illinois and Michigan Canal all converging in the area. The city is also known for its historical architecture and cultural contributions to the region.
Decatur: Located in central Illinois, Decatur grew as an agricultural and manufacturing center, thanks to its strategic position along the rail lines and highways. It remains a hub for grain processing and industrial activity.
3. Historic and Industrial Centers
Aurora: As one of the largest cities in Illinois, Aurora grew rapidly during the 19th century due to its role in the development of the railroad industry. Today, Aurora continues to be an important suburban and industrial center, known for its historic downtown and architecture.
Elgin: Located along the Fox River, Elgin developed as an industrial center in the late 19th and early 20th centuries, particularly known for its watch manufacturing. It has since grown into a significant city in the Chicago metropolitan area, with a mix of suburban development and industry.
Champaign-Urbana: This twin city area in central Illinois is home to the University of Illinois, making it a significant educational and research hub. The city's economy is driven by education, technology, and research industries, and it is an important center for innovation in the state.
Bloomington-Normal: These twin cities in central Illinois are known for their strong agricultural and insurance sectors. Bloomington is home to State Farm Insurance, while Normal hosts Illinois State University, contributing to a vibrant educational and business environment.


Topographic Tour of Illinois
Illinois is known for its relatively flat terrain, but the state offers various unique topographical features worth exploring.
1. Central Lowlands
The central part of Illinois is dominated by flat plains and farmland. This region was shaped by glacial activity during the Ice Ages, leaving behind fertile soils. It is ideal for agriculture, especially corn and soybeans.
2. Eastern Lake Section
Along the eastern side of Illinois, the shores of Lake Michigan provide a unique coastal environment, home to major cities like Chicago and large harbors that play critical roles in commerce and trade.
3. Mississippi Alluvial Plain
Southern Illinois includes the floodplains of the Mississippi River. This area features wetlands, oxbow lakes, and rich, alluvial soils that support a wide range of wildlife and agricultural activities.
4. Driftless Area
In the northwest, Illinois has a section of the Wisconsin Driftless Area, known for its rugged hills, deep valleys, and unique ecosystems, which stand in stark contrast to the surrounding flat terrain.

Physiographic Regions of Illinois
CENTRAL LOWLAND, DISSECTED TILL PLAINS
The Dissected Till Plains are primarily composed of rolling hills, carved out by rivers and streams. This region is mostly agricultural, with soils formed from glacial till, making it highly fertile.
CENTRAL LOWLAND, EASTERN LAKE
This region includes the area surrounding Lake Michigan, where the geography supports large cities, industrial areas, and ports.
CENTRAL LOWLAND, TILL PLAINS
The flat Till Plains region, covering central Illinois, is known for its highly productive agricultural lands, with a significant portion used for corn and soybean farming.
CENTRAL LOWLAND, WISCONSIN DRIFTLESS
This unique region was untouched by glaciers, resulting in rugged hills and valleys. It is located in the far northwestern part of the state.
COASTAL PLAIN, EAST GULF COASTAL PLAIN
The southern tip of Illinois includes part of the East Gulf Coastal Plain, where the terrain is flatter and more suited to agriculture and wetland ecosystems.
COASTAL PLAIN, MISSISSIPPI ALLUVIAL PLAIN
This region, along the western side of Illinois, is characterized by low-lying floodplains along the Mississippi River.
INTERIOR LOW PLATEAUS, HIGHLAND RIM
This region in southern Illinois is characterized by low plateaus and ridges, interspersed with rolling hills and agricultural land.
OZARK PLATEAUS, SPRINGFIELD-SALEM PLATEAUS
The Ozark Plateaus include the Springfield-Salem Plateaus, a region of southern Illinois with rugged terrain, scenic landscapes, and rich biodiversity.

Notable Federal Lands: Some of the Largest and Most Fascinating Destinations in Illinois
1. Shawnee National Forest
Shawnee National Forest, located in southern Illinois, is known for its scenic vistas, rugged terrain, and diverse ecosystems. The forest offers numerous recreational opportunities, including hiking, camping, and rock climbing. Major sites include the Garden of the Gods, Rim Rock, and Bell Smith Springs. The forest is also home to a rich variety of flora and fauna, making it a prime location for nature enthusiasts.
2. Midewin National Tallgrass Prairie
Midewin National Tallgrass Prairie, located southwest of Chicago, is a protected area focused on the restoration of native prairie ecosystems. Visitors can explore miles of hiking and biking trails through the grasslands. The prairie also offers opportunities for bird watching, with many species of migratory birds, and bison have been reintroduced to the area to help restore the ecosystem.
3. Cache River State Natural Area
While not a federal land, Cache River State Natural Area in southern Illinois is one of the state's most unique ecosystems, featuring ancient cypress swamps and a diverse array of plant and animal species. It offers excellent opportunities for kayaking, wildlife viewing, and nature photography. The area is home to several rare and endangered species, as well as some of the oldest trees in Illinois.
4. Upper Mississippi River National Wildlife and Fish Refuge
Spanning four states, including Illinois, the Upper Mississippi River National Wildlife and Fish Refuge is a large and ecologically significant area along the Mississippi River. In Illinois, it offers opportunities for fishing, boating, and bird watching, particularly during migratory seasons. The refuge protects vital wetlands and floodplain ecosystems that are crucial for fish and wildlife.
5. Crab Orchard National Wildlife Refuge
Located near Carbondale in southern Illinois, Crab Orchard National Wildlife Refuge is known for its mix of recreational opportunities and conservation areas. Visitors can enjoy fishing, boating, and camping around Crab Orchard Lake, while the refuge’s diverse ecosystems support a wide range of wildlife, including bald eagles, white-tailed deer, and waterfowl.
6. Illinois and Michigan Canal National Heritage Corridor
The Illinois and Michigan Canal National Heritage Corridor stretches from Chicago to LaSalle and celebrates the history of the canal that connected the Great Lakes to the Mississippi River. While much of the canal is no longer in use, the corridor preserves its historical significance, offering hiking, biking, and interpretive tours along the former towpaths.

Ecoregions of Illinois
1. Central Dissected Till Plains Section
This ecoregion is characterized by rolling hills formed from glacial till, with agriculture being the dominant land use. It is home to a variety of native plants and wildlife, including species adapted to the patchy woodlands and prairies that once dominated the landscape. Today, most of the land is used for corn and soybean production.
2. Central Loess Plains Section
The Loess Plains are composed of wind-deposited silt (loess), which creates highly fertile soils ideal for farming, particularly in central Illinois. The region supports extensive agricultural activities, especially row crops such as corn and soybeans. Remnants of prairie and savanna ecosystems can still be found in some protected areas.
3. Central Till Plains, Beech-Maple Section
This ecoregion features forests dominated by beech and maple trees, with agricultural lands interspersed throughout. The relatively moist climate of this region supports mixed hardwood forests, although much of the area has been cleared for agriculture. Some forested areas still provide important habitats for wildlife and help preserve biodiversity.
4. Central Till Plains, Oak-Hickory Section
The Oak-Hickory section is known for its forests dominated by oak and hickory trees, which are scattered across an agricultural landscape. These forests provide important wildlife habitats, and many state parks and conservation areas are located within this region to protect the remaining woodlands and promote biodiversity.
5. Interior Low Plateau, Shawnee Hills Section
Located in southern Illinois, the Shawnee Hills section is characterized by rugged terrain, bluffs, and steep ridges. It is part of the larger Interior Low Plateau, and the mixed deciduous forests here contain a variety of oak, hickory, and maple species. The region is home to the Shawnee National Forest, a major conservation area offering recreation and biodiversity.
6. Mississippi Alluvial Basin Section
This section lies along the western edge of Illinois, bordering the Mississippi River. It features wetland ecosystems, floodplains, and bottomland forests, which are home to numerous species of migratory birds, waterfowl, and other wildlife. This region plays a critical role in flood control and habitat preservation, particularly in conservation areas like the Upper Mississippi River National Wildlife and Fish Refuge.
7. Southern Till Plains Section
This ecoregion, found in central and southern Illinois, is characterized by flat to gently rolling plains created by glacial till deposits. It is primarily an agricultural region, with large areas dedicated to corn, soybean, and wheat farming. Despite its agricultural focus, there are pockets of prairie, wetlands, and woodlands that provide habitat for native species.
8. Ozark Plateau Section
Located in the southwestern part of Illinois, the Ozark Plateau features rugged topography with steep hills, ridges, and forests. This region is an extension of the larger Ozark Plateau found in Missouri and Arkansas. The area is known for its limestone and sandstone bluffs, as well as caves and springs that support diverse ecosystems.
9. Illinois River Bluffs Section
This section, which runs along the Illinois River, is known for its steep bluffs and deep ravines. The river has carved out this unique landscape over millennia. The area supports forests, prairies, and wetlands, and is a critical migration corridor for birds and other wildlife. Several conservation efforts aim to protect this ecologically important region.
10.Upper Gulf Coastal Plain Section
This section is located in the south part of the state and is known for its distinctive geological, ecological, and biological features that set it apart from other regions in Illinois. This area has bottomland forests, oak-hickory forests, wetlands, and prairies. Major water systems such as the Cache River and Ohio River contribute to the region’s rich wetland ecosystems, supporting a diverse range of aquatic and bird species.