Where is Illinois Located in the United States?

Illinois, located in the Midwestern United States, is a state known for its diverse landscapes, from bustling urban centers like Chicago to vast agricultural plains. Positioned strategically in the heart of the U.S., Illinois is a hub for transportation, commerce, and industry, offering access to both the Great Lakes and the Mississippi River. Illinois’s state facts include: state name: Illinois, postal abbreviation: IL, population: approximately 12.6 million (2024 estimate), area: 57,914 square miles, capital: Springfield, largest city: Chicago, year of statehood: 1818, time zones: Central Time Zone (and a small area in Eastern Time Zone in the far east).

Bordering States

Wisconsin

To the north, Illinois shares a border with Wisconsin that runs for approximately 170 miles. This border is marked by a transition from Illinois’ fertile prairies to Wisconsin’s rolling hills and forests. Major cities near the border include Rockford, IL, and Beloit, WI. The Illinois-Wisconsin boundary is defined by the northern reaches of the Mississippi River and a series of man-made survey lines. Wisconsin’s economy and culture are closely linked with Illinois, especially in the Chicago metropolitan area, where many Wisconsin residents commute to work. This cross-border relationship is evident in the shared transportation networks and trade between the two states.

Iowa

To the west, Illinois shares a lengthy border with Iowa, much of which is defined by the Mississippi River. This border spans approximately 280 miles, creating a natural boundary that separates the two states. The Mississippi River also serves as a major commercial waterway, with cities like Moline, IL and Davenport, IA forming the Quad Cities area, a critical hub for industry and transportation. The Mississippi provides recreational opportunities as well, with both sides of the river offering parks, fishing, and boating activities. This region has strong agricultural ties, with both states relying on the river to transport goods like corn and soybeans.

Missouri

Southwest of Illinois lies Missouri, with a border also primarily defined by the Mississippi River to the east and the Missouri River to the south. The Illinois-Missouri border extends for about 160 miles. This region is known for its blend of rural and industrial areas, with the river playing a key role in the transportation of agricultural and manufactured products. St. Louis, Missouri’s largest city, sits directly across the Mississippi River from East St. Louis, IL, creating an economic and cultural linkage between the two states. The Illinois side is heavily influenced by the St. Louis metropolitan area, sharing industries like manufacturing, transportation, and commerce.

Kentucky

To the southeast, Illinois is bordered by Kentucky, with the Ohio River creating a natural boundary that stretches for about 120 miles. The river forms a significant part of Illinois’ southern border, and towns like Cairo, IL, are situated where the Ohio meets the Mississippi River. This confluence creates a major navigational and trading route. Historically, this area has been vital for shipping goods, and today it continues to serve as a key waterway for barges and shipping industries. The region also has rich agricultural land, especially along the riverbanks, where corn and soybean farming dominate.

Indiana

To the east, Illinois shares a border with Indiana that runs for approximately 230 miles, largely following straight lines determined by early surveyors. This border runs through a mix of urban and rural areas, with cities like Danville, IL, and Terre Haute, IN, serving as important cross-border economic hubs. The Chicago metropolitan area extends into northwestern Indiana, with both states sharing key transportation routes, industries, and cultural ties. Indiana’s proximity to Chicago makes it a significant partner in manufacturing and logistics.

Michigan (Water Border)

While Illinois does not share a land border with Michigan, it is connected to the state through Lake Michigan. Illinois has a shoreline along the southern part of the lake, which serves as a critical waterway for commerce and transportation. Chicago‘s position on Lake Michigan makes it one of the busiest port cities in the world, facilitating trade with Michigan and beyond. This connection to Michigan via the lake enhances Illinois’ role as a shipping hub and strengthens economic ties between the two states.

GPS Coordinates of Illinois

Illinois is geographically located between the latitudes of 36.9703° N to 42.5083° N and the longitudes of 87.4948° W to 91.5123° W, positioning it in the heart of the Midwestern United States. The state is centrally located, making it a critical transportation hub for both the U.S. and international trade. The central coordinates of Illinois are approximately 40.6331° N, 89.3985° W, placing the state firmly in the Central Time Zone. This central location offers access to major markets on both the East Coast and West Coast, as well as easy transportation links to the South.

The state’s proximity to Lake Michigan also plays a vital role in its geography and economy. The Chicago metropolitan area, situated on the western shore of Lake Michigan, is one of the largest economic and transportation centers in the country. From this location, Illinois connects to several major highways, railroads, and shipping routes that make it a key player in the national and international movement of goods.

Illinois is situated in the Interior Plains region, which is characterized by its flat to gently rolling terrain, particularly in the central and northern parts of the state. This flatness makes Illinois an ideal location for agriculture, particularly in the production of corn and soybeans, for which it is one of the leading states in the U.S.

Due to its central position in the country, Illinois experiences a continental climate with four distinct seasons, ranging from cold, snowy winters to hot, humid summers. The geography of the state, including its positioning relative to major rivers like the Mississippi and the Ohio, has shaped its development, particularly in agriculture, trade, and transportation.

Levels of Elevation in Illinois

Illinois is predominantly a flat state, with elevations that range from sea level along the Mississippi River to modest hills in the southern and northwestern regions. The highest point in Illinois is Charles Mound, which rises to an elevation of 1,235 feet (376 meters) above sea level. Charles Mound is located in the far northwestern corner of the state, near the town of Scales Mound, close to the Wisconsin border. This area, part of the Driftless Area, is known for its rolling hills and scenic landscapes, in contrast to the flat terrain that dominates most of Illinois.

The central and southern regions of Illinois are part of the Great Plains, where elevations range from about 300 to 800 feet above sea level. This flat landscape is largely the result of glacial activity during the last Ice Age, which leveled the land and left behind rich, fertile soils. As a result, these areas are among the most productive agricultural regions in the United States, particularly for corn and soybeans.

The lowest point in Illinois is located along the Mississippi River in Alexander County, at an elevation of 280 feet (85 meters) above sea level. This point is near the town of Cairo, where the Mississippi and Ohio Rivers meet, creating a vital confluence for transportation and commerce.

While Illinois is not known for mountainous terrain, the Shawnee Hills in the southern part of the state offer modest elevations that rise to about 1,000 feet. This region, including areas like Garden of the Gods and Shawnee National Forest, is known for its rugged beauty and offers hiking, camping, and outdoor recreational opportunities. The hills are composed of sandstone formations that were left untouched by glaciers, contributing to their unique geological features.

The variation in elevation across Illinois, while modest, still contributes to distinct ecological zones, with the rolling hills in the north and south supporting forests and outdoor recreation, and the flat central plains ideal for large-scale agriculture.

Most Extreme Points of Illinois

Illinois’ most extreme geographical points define the boundaries of the state and showcase the diversity of its landscapes.

• Easternmost point: The easternmost point of Illinois is located near the town of Marshall, in Clark County, along the border with Indiana. This area is part of the Wabash River watershed and features rich agricultural land. The town of Marshall is situated near Interstate 70, a major east-west route that connects Illinois to Indiana and the rest of the Midwest. The flat plains in this region are typical of the eastern part of the state.
• Westernmost point: The westernmost point of Illinois lies near the town of Warsaw, in Hancock County, along the Mississippi River. This area marks the boundary between Illinois and Iowa, with the river creating a natural divide. The region is known for its scenic views of the river and its historic significance in Illinois’ development. The Mississippi River serves as a vital transportation route for goods and materials, particularly in industries like agriculture and manufacturing.
• Southernmost point: The southernmost point of Illinois is located in Cairo, at the confluence of the Mississippi and Ohio Rivers. This point marks the junction where the two major rivers meet, creating a strategic location for river traffic and commerce. Cairo has a rich history as a transportation hub, although its economic prominence has declined over the years. The region is characterized by lowlands, swamps, and floodplains, with agriculture being the dominant industry in the surrounding areas.
• Northernmost point: The northernmost point in Illinois is near the town of South Beloit, in Winnebago County, close to the Wisconsin border. This area is part of the northern agricultural belt and features rolling hills and farmland. South Beloit lies just south of Beloit, Wisconsin, and the region is part of the greater Rockford metropolitan area, a key industrial and economic zone for northern Illinois.

These extreme points illustrate Illinois’ geographic diversity, from river lowlands in the south to rolling hills in the north, each playing a key role in the state’s economy and natural environment.

Major Mountains in Illinois

Illinois is not typically associated with mountainous terrain, as much of the state is composed of flat plains. However, there are several regions in Illinois with significant hills and ridges that offer scenic beauty and outdoor recreational opportunities.

• Charles Mound: At an elevation of 1,235 feet (376 meters), Charles Mound is the highest natural point in Illinois. Located in Jo Daviess County, in the northwestern part of the state, Charles Mound is part of the Driftless Area, a region that escaped glaciation during the last Ice Age. As a result, this area features rolling hills, ridges, and scenic landscapes that are uncommon in the otherwise flat state. Charles Mound is privately owned, but it is open to the public on select days throughout the year, attracting hikers and outdoor enthusiasts.
• Shawnee Hills: The Shawnee Hills are located in southern Illinois and form one of the most significant elevated regions in the state. This area is characterized by ridges, bluffs, and rock formations that were left behind by glacial activity. The Shawnee National Forest covers much of this region, offering opportunities for hiking, camping, and exploring unique geological formations such as the Garden of the Gods, a popular destination with striking sandstone cliffs and rock formations. The Shawnee Hills rise to about 1,000 feet, making them one of the highest areas in southern Illinois.
• Mississippi River Bluffs: Along the western edge of Illinois, particularly near the Mississippi River, a series of bluffs and ridges rise above the river valley. These bluffs are composed of limestone and other sedimentary rock, and they create dramatic overlooks of the Mississippi River. The bluffs are most prominent near towns like Alton and Grafton, where they provide scenic views and outdoor recreation. The bluffs are also important for wildlife, particularly bird species that use the river corridor as a migratory path.
• Pine Hills: Located in Union County, in southern Illinois, the Pine Hills are part of the Shawnee National Forest and rise to about 800 feet. This area is known for its rugged terrain, dense forests, and scenic overlooks. The Pine Hills offer opportunities for hiking, birdwatching, and exploring the natural beauty of southern Illinois.

Although Illinois lacks towering mountains, the state’s hills and elevated regions provide important ecological zones and outdoor recreation areas. These regions contrast sharply with the flat agricultural plains that dominate much of Illinois’ landscape.

Major Rivers and Lakes in Illinois

Illinois is home to several significant rivers and lakes, many of which play critical roles in the state’s economy, transportation, and recreation.

• Mississippi River: The Mississippi River forms the western border of Illinois, running for approximately 580 miles along the state’s edge. As one of the longest and most important rivers in North America, the Mississippi serves as a vital transportation route for goods, particularly agricultural products like corn and soybeans. The river is also a popular destination for recreation, with numerous parks, fishing spots, and boating opportunities along its banks. Cities like Moline, Rock Island, and Alton are key riverfront communities that rely on the Mississippi for trade and commerce.
• Illinois River: The Illinois River flows through the central part of the state, covering a distance of about 273 miles. It begins near Chicago and winds through cities like Peoria and Ottawa before emptying into the Mississippi River. The Illinois River is one of the most important inland waterways in the state, serving as a major route for barge traffic. The river is also essential for wildlife, particularly migratory birds, and is home to several wildlife refuges and conservation areas.
• Ohio River: Forming the southern border of Illinois, the Ohio River runs for about 130 miles along the edge of the state, separating it from Kentucky. The Ohio River plays a crucial role in transportation and trade, especially at the confluence with the Mississippi River near Cairo. The river is a key waterway for industries like coal, steel, and agriculture, with barges transporting goods up and down the river. The Ohio River also supports recreational activities such as fishing and boating.
• Lake Michigan: Illinois has a 63-mile shoreline along Lake Michigan, the only one of the Great Lakes that borders the state. The lake is a crucial resource for Illinois, particularly for the city of Chicago, which relies on it for transportation, drinking water, and recreation. Chicago’s harbor on Lake Michigan is one of the busiest ports in the world, facilitating trade with other Great Lakes states and Canada. The lake is also a popular destination for swimming, boating, and fishing, with beaches and parks lining the shoreline.
• Carlyle Lake: Located in southern Illinois, Carlyle Lake is the largest man-made lake in the state, covering over 26,000 acres. The lake was created by the U.S. Army Corps of Engineers and serves as a flood control reservoir. It is a popular destination for outdoor activities, including boating, fishing, and camping. The lake is stocked with various fish species, making it a favorite spot for anglers.
• Rend Lake: Another large man-made lake, Rend Lake, is located in southern Illinois and covers about 19,000 acres. It was created by damming the Big Muddy River and is used for flood control, water supply, and recreation. Rend Lake is known for its excellent fishing, particularly for bass, catfish, and crappie. The surrounding Rend Lake State Park offers hiking, camping, and golfing.

Illinois’ rivers and lakes are essential to the state’s economy, environment, and quality of life. They support industries like agriculture, transportation, and tourism, while also providing residents and visitors with abundant opportunities for outdoor recreation. The state’s waterways are integral to its identity, shaping both its natural landscapes and its industrial development.