Thegeography of Indiana comprises the physical features of the land and relative location ofU.S.State ofIndiana. Indiana is in the north-centralUnited States and borders onLake Michigan. Surrounding states areMichigan to the north and northeast,Illinois to the west,Kentucky to the south, andOhio to the east. The entire southern boundary is theOhio River.

• Total area is 36,419.55 square miles (94,326.2 km²), making Indiana the 38th largest in size out of the 50 states.^[1]
• Lake Michigan is the largest body of water wholly or partially within the state borders.
• Hoosier Hill inWayne County is the highest point in the state at 1,257 feet (383 m) above sea level.
• The lowest natural point is on theOhio River, specifically where Illinois, Indiana, and Kentucky meet at one place. The elevation there is 332.50 feet (101.35 m) above sea level.

Indiana is bordered on the north byLake Michigan and the state ofMichigan; on the east byOhio; on the south byKentucky, with which it shares theOhio River as a border; and on the west byIllinois. Indiana is one of theGreat Lakes states.

The northern boundary of the states of Ohio, Indiana, and Illinois was originally defined to be a latitudinal line drawn through the southernmost tip of Lake Michigan. Since such a line did not provide Indiana with usable frontage on the lake, its northern border was shifted ten miles (16 km) north when it was granted statehood in 1816.^[2]

The 475 miles (764 km) longWabash River bisects the state from northeast to southwest before flowing south, mostly along the Indiana-Illinois border. The river has given Indiana a few theme songs, such asOn the Banks of the Wabash,The Wabash Cannonball andBack Home Again, In Indiana.^[3][4] The Wabash is the longest free-flowing river east of theMississippi River, traversing 400 miles (640 km) from the Huntington dam to the Ohio River. TheWhite River, a tributary of the Wabash, zigzags through central Indiana.

There are 24Indiana state parks, nine artificialreservoirs, and hundreds of lakes in the state. Areas under the control and protection of theNational Park Service or theUnited States Forest Service include:^[5][6]

• George Rogers Clark National Historical Park inVincennes
• Indiana Dunes National Park nearMichigan City
• Lincoln Boyhood National Memorial inLincoln City
• Hoosier National Forest inBedford

The state of Indiana can be divided into several distinct regions.

• Northwest (Hammond) – Lake, Porter, La Porte, Jasper, Starke, Newton, Pulaski
• North Central (South Bend) – St. Joseph, Elkhart, Kosciusko, Marshall, Fulton
• North East (Fort Wayne) – Allen, Noble, De Kalb, Lagrange, Huntington, Adams, Whitley, Steuben, Wells
• Lower Northwest (Lafayette) – Tippecanoe, Montgomery, Clinton, White, Carroll, Fountain, Benton, Warren
• Lower North Central (Kokomo) – Howard, Cass, Miami, Wabash, Tipton
• West Central (Terre Haute) – Vigo, Clay, Sullivan, Parke, Vermillion
• Central (Indianapolis) – Marion, Hamilton, Hendricks, Johnson, Hancock, Boone, Morgan, Shelby, Putnam
• East Central (Muncie) – Madison, Delaware, Grant, Wayne, Henry, Randolph, Fayette, Jay, Rush, Blackford, Union
• Central Southwest (Bloomington) – Monroe, Greene, Owen
• Central Southeast (Columbus) – Bartholomew, Dearborn, Jackson, Lawrence, Ripley, Jennings, Decatur, Franklin, Brown
• Southwest (Evansville) – Vanderburgh, Warrick, Dubois, Knox, Daviess, Gibson, Posey, Spencer, Perry, Pike, Martin
• Southeast (Jeffersonville /New Albany) – Clark, Floyd, Harrison, Jefferson, Washington, Scott, Orange, Crawford, Switzerland, Ohio

Northern Indiana consists of 26 counties in the northern third of the state.

The landscape is characterized physically by very flat to rolling terrain ranging from 600 to 1,000 feet (180 to 300 m) above sea level and is similar to central Indiana except for the presence of higher and hillierterminal moraines and many glacialkettle lakes in some areas. Sand dunes and sand ridges also exist along the Lake Michigan shoreline(some reaching near 200 feet in height) and inland around theKankakee River Basin. TheSaint Lawrence River Divide goes through Northern Indiana following the top of theValparaiso Moraine part of the way. Besides someurban areas, much of Northern Indiana is farmland.

Heavy industry is as much a part of the economy in the eastern two thirds of Northern Indiana as agriculture, and, as a result, the region tends to be associated with theRust Belt. Northern Indiana as a whole is also the most ethnically diverse region in Indiana.

The northwest corner of the state is part of theChicago metropolitan area and has nearly one million residents.^[7]Gary, and the cities and towns that make up the northern half ofLake,Porter, andLa Porte Counties bordering onLake Michigan, are effectively commuter suburbs of Chicago. Porter and Lake counties are commonly referred to as "The Calumet Region". The name comes from the fact that theGrand Calumet River and Little Calumet rivers run through the area. These counties are in the CentralTime Zone, the same as Chicago.NICTD owns and operates theSouth Shore Line, a commuter rail line that runs electric-powered trains betweenSouth Bend andChicago.^[8] Sand dunes and heavy industry share the shoreline of Lake Michigan in northern Indiana. Along the shoreline of Lake Michigan inNorthern Indiana one can find many parks between the industrial areas. TheIndiana Dunes National Park and theIndiana Dunes State Park are two natural landmarks of the area.

Northwest Indiana is marked withswell andswale topography as it retreats South from Lake Michigan (which are remnants of the beaches of ancient Lake Michigan) and is one of the marshiest parts of the state. The ecology changes dramatically between swells, or on opposite sides of the same swell. Plants and animals adapted to marshes are generally found in the swales, while forests or evenprickly pear cactus andsix-lined racerunners are found in the dryer swells.^[9]

TheKankakee River, which winds through northern Indiana, serves somewhat as a demarcating line between suburban northwest Indiana and the rest of the state.^[10] Before it was drained and developed for agriculture, the Kankakee Marsh was one of the largest freshwater marshes in the country.^[11] South of the Kankakee is a large area ofprairie, the eastern edge of the Grand Prairie that coversIowa andIllinois.^[12] Theprairie chicken andAmerican bison were common in Indiana's pioneer era, but are now extinct as wild species within the state.

The South Bend metropolitan area, in north central Indiana, is the center of commerce in the region better known asMichiana. Other cities located within the area includeElkhart,Mishawaka,Goshen, andWarsaw.Fort Wayne, the state's second largest city, is located in the northeastern part of the state where it serves the state as a transportation hub. Other cities located within the area includeHuntington andMarion. East of Fort Wayne is an area of extremely flat land that, before development, was the westernmost reach of theGreat Black Swamp.^[13]

Northeastern Indiana is home to a number of lakes, many of which arekettle lakes, which were caused by the glaciers that covered Indiana thousands of years ago andGlacial Lake Maumee. Some of these lakes include Lake James inPokagon State Park,Lake Maxinkuckee,Lake Wawasee andLake Tippecanoe. Lake Wawasee is the largest natural lake in Indiana, while Lake Tippecanoe is the deepest lake, reaching depths of over 120 feet (37 m). Both lakes are located inKosciusko County.Chain O' Lakes State Park, located inNoble County, contains 11 lakes, 8 of which are connected by natural channels.

The center third of this region is known as the Indiana section ofMichiana.South Bend is the cultural and economic center of the Michiana region.

The eastern third of this region centers around theFort Wayne area and theMaumee River basin.

Central Indiana comprises the 33 counties in the middle third of the state. However, many Hoosiers, or people living in Indiana, consider central Indiana as theIndianapolis metropolitan area.^{[citation needed]} The region's dominant city isIndianapolis, the state capital and most populous city in Indiana. Other prominent cities includeAnderson,Kokomo,Lafayette,Muncie,Richmond, andTerre Haute. Home to about 3.3 million people, Central Indiana is the most populous of the state's three regions.

Physically, the land in Central Indiana is characterized primarily by low, gently rolling hills and shallow valleys. Some counties of the region, likeHoward County, are generally flat, while others, such asMorgan County, are more rugged and hilly.Tippecanoe County is trisected by theWabash River,Tippecanoe River, andWildcat Creek, has perhaps the most diverse physiography of the region. Elevation ranges from 600 to 1,000 feet (180 to 300 metres)above sea level. Forests and farmland line Central Indiana's gently rolling plains and river valleys. The highest point in Indiana isHoosier Hill, at 1,257 feet (383 m) above sea level in northernWayne County. Rural areas in the central portion of the state are typically composed of a patchwork offields andforested areas. The geography of Central Indiana consists of gently rolling hills andsandstone ravines carved out by the retreating glaciers. Many of these ravines can be found in west-central Indiana, specifically alongSugar Creek inTurkey Run andShades state parks.

Central Indiana's economy is primarily driven by health and education, agriculture, and manufacturing. Major universities includeBall State University,Butler University,Purdue University,Indiana State University,Indiana University Indianapolis, andIndiana Wesleyan University, among several other private liberal arts colleges, such asDePauw,Earlham,Franklin, andWabash.

Evansville, the third largest city in Indiana, is located in the southwestern corner of the state. It is located in atri-state area that includes Illinois, Indiana, and Kentucky. The southern cities ofClarksville,Jeffersonville, andNew Albany are part of theLouisville metropolitan area and are in the area called Kentuckiana.Bloomington, the home of Indiana University's main campus, andColumbus, a small industrial city, are located in the northern part of this region called south-central Indiana.Vincennes, founded by French traders in 1732 and the oldest settlement in the state, is located on theWabash River and served as the first capital of the Indiana Territory. Vincennes is also home of thePantheon Theatre. Indiana was settled from its southern periphery northward; many more of its oldest settlements, including its first capital,Corydon, are in southern Indiana. Until 1950, theUnited States Census found thecenter of population to lie in southern Indiana.

Southern Indiana is a mixture of farmland, forest and very hilly areas, especially near Louisville and in the south central lime hills areas, stretching from the Ohio River to as far north asGreencastle, to the wide, flat valleys along the Wabash and Ohio rivers. TheHoosier National Forest is a 200,000-acre (810 km²) nature preserve in south-central Indiana. Southern Indiana's topography is more varied than that in the north and generally contains more hills and geographic variation than the northern portion, such as the"Knobs", a series of 1,000 ft (300 m) hills that run parallel to the Ohio River in south-central Indiana. The largely flat and flood-prone bottomlands of Indiana, where the Wabash, White, and Ohio Rivers converge, hosts numerous plant and animal species normally found in the Lower Mississippi and Gulf Coast region of the United States.^[14]Brown County is well known for its hills covered with colorful autumn foliage, theformer home ofT. C. Steele, andNashville, the county seat and shopping destination. Harrison and Crawford Counties boast three of the state's most popular commercial caves atWyandotte,Marengo, andSquire Boone Caverns.

Thelimestone geology of Southern Indiana has created numerous caves and one of the largest limestone quarry regions in the United States. Many of Indiana's official buildings, such as theIndiana Statehouse, the downtown monuments, the Indiana University School of Law in Indianapolis, many buildings atIndiana University Bloomington, and theIndiana Government Center, are all examples of Indiana architecture made with Indiana limestone. Indiana limestone has also been used in many other famous structures in the United States, such as theEmpire State Building, thePentagon, and theWashington National Cathedral. In addition, 35 of the 50 state capitols are made of Indiana limestone.^[15]

Indiana is broken up into three main physical regions: The Great Lakes Plain in the northern third of the state, the Tipton Till Plain in the central third, and the Southern Hills and Lowlands region in the southern third.

Two-thirds of Indiana is covered with glacial till, from a few feet to hundreds of feet thick. The visible geology of the State is therefore mainlyQuaternary, with rocks buried deeply. The southern third of the state is unglaciated and the bedrock becomes visible. TheCincinnati Arch and theKankakee Arch are the predominant geologic features which control the underlying bedrock.^[16]The oldest bedrock isOrdovician, forming an arch across the state from the southeastern corner nearCincinnati north and westward to the northwestern corner nearChicago. These layers ofshale andlimestone are exposed at the surface only in the southern reaches. Parallel to this line on north and south edges is a narrow band ofSilurian age bedrock. These are primarily limestone anddolomite. The next band of rocks areDevonian in age and pass underLafayette,Indianapolis andNew Albany, across the Ohio River fromLouisville. Greater erosion and thinner layers of glacial till have created surface exposures along river vallies. The last band of bedrock is from theCarboniferous age and covers nearly a third of the state's southwestern area. There the state's ‘coal measures’ are exposed and major surface mining activities have built the local economies. A narrow belt ofMississippian age limestone, shale, andsandstone occurs west and southwards ofBloomington and had become known for its production ofIndiana Limestone an important building material.^[17]

Indiana's ‘Coal Measures’ are in the southwest corner of the state, where thebedrock is of thePennsylvanian era.^[18]

TheWabash River is the longest river in Indiana and cuts across the state from east to west. The Wabash and its main tributaries, theSalamonie River,Mississinewa River,Eel River,Tippecanoe River,White River,Vermilion River, andEmbarras River drain Central Indiana. TheIroquois andKankakee Rivers begin in Indiana and flow westward intoIllinois before reaching theMississippi River. TheSt. Joseph River flows from the state ofMichigan through the northern counties atSouth Bend before returning to Michigan and ending at Lake Michigan. TheMaumee River in the northeast is formed by theSt. Mary's River and theSt. Joseph River, which join inFort Wayne before flowing into the state ofOhio to end atLake Erie. TheOhio River forms the southern boundary of the State, draining the lower two tiers of counties.

• Indiana
• List of counties in Indiana
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