The Erie Canal brought increased commercial activity in the Great Lakes, and the invention of the self-scouring steel plow by Illinoisan John Deere turned the state's rich prairie into some of the world's most productive and valuable farmland, attracting immigrant farmers from Germany, Sweden and elsewhere.

In the mid-19th century, the Illinois and Michigan Canal and a sprawling railroad network facilitated trade, commerce, and settlement, making the state a transportation hub for the nation.

[7] The Great Migration from the South established a large Black community, particularly in Chicago, which became a leading cultural, economic, and population center; its metropolitan area, informally referred to as Chicagoland, holds about 65% of the state's 12.8 million residents.

Three U.S. presidents have been elected while residents of Illinois: Abraham Lincoln, Ulysses S. Grant, and Barack Obama; additionally, Ronald Reagan was born and raised in the state.

Illinois has a highly diverse economy, with the global city of Chicago in the northeast, major industrial and agricultural hubs in the north and center, and natural resources such as coal, timber, and petroleum in the south.

Owing to its central location and favorable geography, the state is a major transportation hub: the Port of Chicago has access to the Atlantic Ocean through the Great Lakes and Saint Lawrence Seaway and to the Gulf of Mexico from the Mississippi River via the Illinois Waterway.

They built an urban complex of more than 100 platform and burial mounds, a 50-acre (20 ha) plaza larger than 35 football fields,[18] and a woodhenge of sacred cedar, all in a planned design expressing the culture's cosmology.

[24] As the Illini declined during the Beaver Wars era, members of the Algonquian-speaking Potawatomi, Miami, Sauk, and other tribes including the Fox (Meskwaki), Iowa, Kickapoo, Mascouten, Piankeshaw, Shawnee, Wea, and Winnebago (Ho-Chunk) came into the area from the east and north around the Great Lakes.

[37] In 1832, the Black Hawk War was fought in Illinois and present-day Wisconsin between the United States and the Sauk, Fox (Meskwaki), and Kickapoo Indian tribes.

Located in Hancock County along the Mississippi River, Nauvoo flourished and, by 1844, briefly surpassed Chicago for the position of the state's largest city.

Following a succession crisis, Brigham Young led most Latter Day Saints out of Illinois in a mass exodus to present-day Utah; after close to six years of rapid development, Nauvoo quickly declined afterward.

In 1847, after lobbying by Dorothea L. Dix, Illinois became one of the first states to establish a system of state-supported treatment of mental illness and disabilities, replacing local almshouses.

[42] During the American Civil War, Illinois ranked fourth in soldiers who served (more than 250,000) in the Union Army, a figure surpassed by only New York, Pennsylvania, and Ohio.

[43] The town of Cairo, at the southern tip of the state at the confluence of the Mississippi and Ohio Rivers, served as a strategically important supply base and training center for the Union army.

[45] Bolstered by continued immigration from southern and eastern Europe, and by the African-American Great Migration from the South, Illinois grew and emerged as one of the most important states in the union.

[63] During the early part of the Paleozoic Era, the area that would one day become Illinois was submerged beneath a shallow sea and located near the Equator.

Illinois's eastern border with Indiana consists of a north–south line at 87° 31′ 30″ west longitude in Lake Michigan at the north, to the Wabash River in the south above Post Vincennes.

In extreme northwestern Illinois, the Driftless Area, a region of unglaciated and therefore higher and more rugged topography, occupies a small part of the state.

As defined by the federal government, the Chicago metro area includes several counties in Illinois, Indiana, and Wisconsin, and has a population of over 9.8 million.

[25][67] This region has a somewhat warmer winter climate, different variety of crops (including some cotton farming in the past), more rugged topography (due to the area remaining unglaciated during the Illinoian Stage, unlike most of the rest of the state), as well as small-scale oil deposits and coal mining.

By several metrics, including racial and ethnic background, religious affiliation, and percentage of rural and urban divide, Illinois is the most representative of the larger demography of the United States.

[161] By the early 2000s, Illinois's economy had moved toward a dependence on high-value-added services, such as financial trading, higher education, law, logistics, and medicine.

[162] Mattoon was chosen as the site for the Department of Energy's FutureGen project, a 275-megawatt experimental zero emission coal-burning power plant that the DOE just gave a second round of funding.

[176][177] University of Illinois Urbana-Champaign is one of the partners in the Energy Biosciences Institute (EBI), a $500 million biofuels research project funded by petroleum giant BP.

However, in recent elections, the Democratic Party has gained ground, and Illinois has come to be seen as a solid "blue" state in both presidential and congressional campaigns.

Politics in the state have been infamous for highly visible corruption cases, as well as for crusading reformers, such as governors Adlai Stevenson and James R. Thompson.

On December 7, 2011, former governor Rod Blagojevich was sentenced to 14 years in prison for allegations that he conspired to sell the vacated Senate seat left by President Barack Obama to the highest bidder.

In 1912, William Lorimer, the GOP boss of Chicago, was expelled from the U.S. Senate for bribery, and in 1921, Governor Len Small was found to have defrauded the state of a million dollars.

Ulysses S. Grant was born in Ohio and had a military career that precluded settling down, but on the eve of the Civil War and approaching middle age, he moved to Illinois and thus utilized the state as his home and political base when running for president.

Illinois also has more than twenty additional accredited four-year universities, both public and private, and dozens of small liberal arts colleges across the state.