Illinois is a big state, but one which in recent years has been moving into the Democrat column.
Although the congressional delegation remains evenly split, in 2002 Democrats won control of the governor's mansion, and they also control the state House and Senate.
In 2000 Illinois voted for the losing candidate for only the second time in 80 years. Still, the record isn't bad: in the last 46 presidential elections, Illinois has picked the winner 39 times.
Population: 12,419,293 (ranked 5 among states)
Governor: Rod Blagojevich (D)
Electoral College votes: 21
The Democrats dominated Chicago's politics for most of the 20th Century. Party bosses had influence at all levels of society, controlling appointments and patronage and engineering the vote.
Amongst these was legendary Chicago Mayor Richard Daley, who had a dramatic effect on two presidential contests.
In 1960, he was instrumental in rousing support for John F Kennedy, and in 1968 his police clashed with demonstrators at the Democratic Convention, damaging the city's political psyche and the party's image.
House of Representatives:
9 Democrat, 10 Republican
Senate: 1 Democrat, 1 Republican
The Democratic Convention returned in 1996 and the political machine has largely gone. But the current, highly popular Chicago mayor is Richard Daley's son.
Illinois is an industrial leader. By the end of the 19th Century the state was established as a centre of urban industry. Chicago grew as the rail network spread and soon became the leader in the US's meatpacking industry.
It is still an important manufacturing centre and it has the largest service and white-collar sector in the interior of the US. But now the trading of commodities, rather than of meat, dominates the city's economy.
2000: Gore 55%, Bush 43%
1996: Clinton 49%, Dole 37%
1992: Clinton 49%, Bush 34%, Perot 17%
Illinois's economy has attracted millions of immigrants to Chicago over the decades, and it is now the third largest city in the US, with the world's second biggest airport and a university that employs more Nobel laureates than any other in the world.