1980 United States presidential election in Illinois

The 1980 United States presidential election in Illinois took place on November 4, 1980. All 50 states and The District of Columbia, were part of the 1980 United States presidential election. State voters chose 26 electors to the Electoral College, who voted for president and vice president. Illinois voters chose between the Democratic ticket of incumbent president Jimmy Carter and vice president Walter Mondale, and the Republican ticket of Ronald Reagan and running mate George H. W. Bush, as well as the independent candidacy of John B. Anderson and running mate Patrick Lucey.

Illinois had voted Republican in the previous three presidential elections, and early analysis suggested that Reagan was a strong candidate against Carter in Dixie Southern Illinois. Nonetheless, at the beginning of the campaign trail one opinion poll suggested Reagan would lose to Carter by 26%, but the Republican campaign knew carrying a state which Gerald Ford had won four years ago to be essential and the state was heavily targeted by GOP campaigners. By mid-September, polls were showing Illinois as very close, and Carter was hit by political conflicts in Chicago between mayor Jane Byrne and State Senator Richard Daley.

Carter strategists did target the state in September and hoped that prospective Republican nominee John Anderson – who had run against Reagan in the Republican primary before launching his own independent presidential campaign – would take enough votes from Reagan for Carter to obtain a narrow victory. Polls in mid-October suggested that Illinois was "too close to call", and as election day neared, opinions fluctuated especially in the critical southern part of the state.

Ultimately Illinois—the state where Reagan was born and raised, and where Anderson served as a Congressman—was carried by the Republican ticket by a 7.93% margin of victory over the Democrats. Reagan won all but three counties, although Carter's 268,000-vote margin in massively populated Cook County meant Illinois nonetheless voted roughly 1.77% more Democratic than the nation at-large. Despite being Anderson's home state, the independent only won 7.30% of the popular vote in Illinois, or 346,754 votes, and he failed to carry any counties.

This would be the last time that Rock Island County voted Republican, as it has since turned sharply to the Democratic Party.

The primaries and general elections coincided with those for other federal offices (Senate and House), as well as those for state offices.

Turnout in the primary elections was 40.41%, with a total of 2,331,148 ballots cast. The primaries saw a cumulative increase in turnout over the previous 1976 primaries.

Turnout during the general election was 76.24%, with 4,749,721 ballots cast.

State-run primaries were held for the Democratic and Republican parties on March 18. The Illinois primaries were viewed as significant in 1980, being viewed as the first large contest in a northern industrial state.

The 1980 Illinois Democratic presidential primary was held on March 18, 1980, in the U.S. state of Illinois as one of the Democratic Party's statewide nomination contests ahead of the 1980 presidential election.

The popular vote was a "beauty contest". Delegates were instead selected by direct-vote in each congressional district on delegate candidates who had either pledged to support a candidate or indicated they would be uncommitted. 138 delegates pledged Jimmy Carter won, while only 14 delegates pledged to Kennedy won. Additionally, 13 uncommitted delegates won. At the state convention in April, Carter was awarded an additional 25 delegates out of the 28 delegates selected at the convention.

The 1980 Illinois Republican presidential primary was held on March 18, 1980, in the U.S. state of Illinois as one of the Republican Party's statewide nomination contests ahead of the 1980 presidential election.

The primary was a so-called "blind primary" or "loophole primary". Under this format, the presidential preference vote was a “beauty contest”. Delegates were not selected based upon the preference vote for president, but rather directly voted upon by voters in each congressional district. Additionally, the presidential preferences of each delegate candidate was not listed on the ballot.

This primary saw a larger-than-usual turnout for an Illinois Republican primary, with more than a 400,000 vote increase over the 1976 Republican primary. This was attributed to both the appeal of Anderson and Reagan to independents as well as crossover voting by Democrats who opted against voting in the Democratic primary due to it lacking a close race.

In both the state's popular vote and delegate count, Ronald Reagan placed first, respectively followed by John B. Anderson, George Bush, and Phil Crane.

Three of the candidates had Illinois connections. Ronald Reagan was born in the state, while John B. Anderson and Phil Crane were both incumbent congressmen from the state. While John B. Anderson failed to win his home state, he performed strongly in certain areas of the state, particularly in the suburbs of Chicago. Phil Crane's securing of three delegates came despite him having already dropped-out of the race before the Illinois primary.

• Brown
• Calhoun
• Cass
• Christian
• Cumberland
• Fayette
• Franklin
• Gallatin
• Greene
• Hamilton
• Hardin
• Jackson
• Jefferson
• Jersey
• Macon
• Macoupin
• Madison
• Marion
• Mason
• Massac
• Montgomery
• Moultrie
• Perry
• Pike
• Pulaski
• Randolph
• Rock Island
• Saline
• Shelby
• Union
• White
• Williamson

• United States presidential elections in Illinois