The dollar gross state product for Illinois was estimated to be US$634 billion in 2008. The state's 2008 per capita gross state product was estimated to beUS$40,006, and the state's per capita personal income was estimated to be US$41,411 in 2009.
As of March 2010, the state's unemployment rate was 11.5%, and two months later, the rate dropped to 10.8% in May.
Illinois' state income tax is calculated by multiplying net income by a flat rate. In 1990, that rate was set at 3%, but in 2010, the General Assembly voted in a temporary increase in the rate to 5%; the new rate went into effect on January 1, 2011, and is scheduled to return to 3% after four years. There are two rates for state sales tax: 6.25% for general merchandise and 1% for qualifying food, drugs and medical appliances. The property tax is the largest single tax in Illinois, and is the major source of tax revenue for local government taxing districts. The property tax is a local — not state — tax, imposed by local government taxing districts, which include counties, townships, municipalities, school districts and special taxation districts. The property tax in Illinois is imposed only on real property.
Illinois' major agricultural outputs are corn, soybeans, hogs, cattle, dairy products, and wheat. In most years, Illinois is either the first or second state for the highest production of soybeans, with a harvest of 427.7 million bushels (11.64 million metric tons) in 2008, after Iowa's production of 444.82 million bushels (12.11 million metric tons). Illinois ranks second in U.S. corn production with more than 1.5 billion bushels produced annually. Illinois also produces wine, and the state is home to two American viticultural areas. Illinois' universities are actively researching alternative agricultural products as alternative crops.
Illinois is one of the nation's manufacturing leaders, boasting annual value added productivity by manufacturing of over $107 billion in 2006. About three-quarters of the state's manufacturers are located in the Northeastern Opportunity Return Region, with 38 percent of Illinois' approximately 18,900 manufacturing plants located in Cook County. As of 2006, the leading manufacturing industries in Illinois, based upon value-added, were chemical manufacturing ($18.3 billion), machinery manufacturing ($13.4 billion), food manufacturing ($12.9 billion), fabricated metal products ($11.5 billion), transportation equipment ($7.4 billion), plastics and rubber products ($7.0 billion), and computer and electronic products ($6.1 billion).
By the early 2000s, Illinois' economy had moved toward a dependence on high-value-added services, such as financial trading, higher education, law, logistics, and medicine. In some cases, these services clustered around institutions that hearkened back to Illinois' earlier economies. For example, the Chicago Mercantile Exchange, a trading exchange for global derivatives, had begun its life as an agricultural futures market. Other important non-manufacturing industries include publishing, tourism, and energy production and distribution.
Illinois is a net importer of fuels for energy, despite large coal resources and some minor oil production. Illinois exports electricity, ranking fifth among states in electricity production and seventh in electricity consumption.
The coal industry of Illinois has its origins in the middle 19th century, when entrepreneurs such as Jacob Loose discovered coal in locations such as Sangamon County. Jacob Bunn contributed to the development of the Illinois coal industry, and was a founder and owner of the Western Coal & Mining Company of Illinois. About 68% of Illinois has coal-bearing strata of the Pennsylvanian geologic period. According to the Illinois State Geological Survey, 211 billion tons of bituminous coal are estimated to lie under the surface, having a total heating value greater than the estimated oil deposits in the Arabian Peninsula. However, this coal has a high sulfur content, which causes acid rain unless special equipment is used to reduce sulfur dioxide emissions. Many Illinois power plants are not equipped to burn high-sulfur coal. In 1999, Illinois produced 40.4 million tons of coal, but only 17 million tons (42%) of Illinois coal was consumed in Illinois. Most of the coal produced in Illinois is exported to other states, while much of the coal burned for power in Illinois (21 million tons in 1998) is mined in the Powder River Basin of Wyoming.
Mattoon was recently chosen as the site for the Department of Energy's FutureGen project, a 275 megawatt experimental zero emission coal-burning power plant which just received a second round of funding from the DOE.
Illinois is a leading refiner of petroleum in the American Midwest, with a combined crude oil distillation capacity of nearly 900,000 barrels per day (143,000 m3/d). However, Illinois has very limited crude oil proved reserves that account for less than 1% of U.S. crude oil proved reserves. Residential heating is 81% natural gas compared to less than 1% heating oil. Illinois is ranked 14th in oil production among states, with a daily output of approximately 28,000 barrels (4,500 m3) in 2005.
Nuclear power arguably began in Illinois with the Chicago Pile-1, the world's first artificial self-sustaining nuclear chain reaction in the world's first nuclear reactor, built on the University of Chicago campus. There are six operating nuclear power plants in Illinois: Braidwood; Byron; Clinton; Dresden; LaSalle; and Quad Cities. With the exception of the single-unit Clinton plant, each of these facilities has two reactors. Three reactors have been permanently shut down and are in various stages of decommissioning: Dresden-1 and Zion-1 and 2. As of 2008, Illinois was ranked first among the 50 states both in nuclear capacity and nuclear generation. In 2007, 48% of Illinois' electricity was generated using nuclear power.
Illinois has seen growing interest in the use of wind power for electrical generation. Most of Illinois was rated in 2009 as "marginal or fair" for wind energy production by the U.S. Department of Energy, with some western sections rated "good" and parts of the south rated "poor". These ratings are for wind turbines with 50-metre (160 ft) hub heights; newer wind turbines are taller, enabling them to reach stronger winds farther from the ground. As a result, more areas of Illinois have become prospective wind farm sites. As of September 2009, Illinois had 1116.06 MW of installed wind power nameplate capacity with another 741.9 MW under construction. Illinois ranked ninth among U.S. states in installed wind power capacity, and sixteenth by potential capacity. Large wind farms in Illinois include Twin Groves, Rail Splitter, EcoGrove, and Mendota Hills.
As of 2007, wind energy represented only 1.7% of Illinois' energy production, and it was estimated that wind power could provide 5-10% of the state's energy needs.Also, the Illinois General Assembly mandated in 2007 that by 2025, 25% of all electricity generated in Illinois is to come from renewable resources.
Illinois is ranked second in corn production among U.S. states, and Illinois corn is used to produce 40% of the ethanol consumed in the United States. The Archer Daniels Midland corporation in Decatur, Illinois is the world's leading producer of ethanol from corn.
University of Illinois at Urbana-Champaign is one of the partners in the Energy Biosciences Institute (EBI), a $500 million biofuels research project funded by petroleum giant BP.