The Cook County, Illinois, general election was held on November 4, 1986.
Primaries were held March 18, 1986.
Elections were held for the offices of Assessor, Clerk, Sheriff, State's Attorney, Superintendent of Education Service Region, Treasurer, President of the Cook County Board of Commissioners, all 17 seats of the Cook County Board of Commissioners, both seats of the Cook County Board of Appeals, 3 seats on the Water Reclamation District Board, and judgeships on the Circuit Court of Cook County.
1986 was a midterm election year in the United States. The primaries and general elections for Cook County races coincided with those for federal (Senate and House) and those for state elections.
The general election saw turnout of 55.95%, with 1,476,370 ballots cast. Chicago saw 841,085 ballots cast, and suburban Cook County saw 635,2865 ballots cast.
Ballots had a straight-ticket voting option in 1986.
In the 1986 Cook County Assessor election, incumbent third-term assessor Thomas Hynes, a Democrat, was reelected.
By winning the Republican nomination, Le Roy M. Graham became the first black candidate to run countywide as a Republican nominee.
In the 1986 Cook County Clerk election, incumbent third-term clerk Stanley Kusper, a Democrat, was reelected.
Incumbent Stanley Kusper defeated two challengers to win renomination.
The more successful of Kusper's two challengers was Jeanne Quinn, who four years earlier had become the first Democrat to be elected to the Cook County Board of Commissioners from suburban Cook County in half a century. Instead of seeking reelection, she instead opted to launch a challenge to Kusper. Kusper's other challenger was 28-year-old millionaire businessman Patrick M. Finley.
Former Illinois state representative Diana Nelson won the Republican primary.
In the 1986 Cook County Sheriff election, incumbent fourth-term sheriff Richard Elrod, a Democrat, was defeated by Republican James E. O'Grady.
O'Grady became the first Republican elected to a countywide executive office in Cook County since Bernard Carey was elected to his final term as Cook County State's Attorney in 1976.
O'Grady won the endorsement of the Chicago Tribune for the general election.
O'Grady's victory came from winning the county's suburbs by a 2-1 margin. He also performed well in some of the ethnically white wards of Chicago, being able to cary 14 of the city's 50 wards.
In the 1986 Superintendent of the Cook County Education Service Region election, incumbent third-term superintendent Richard J. Martwick, a Democrat, was reelected.
No candidate ran in the Republican primary. The Republican Party ultimately nominated Tony Torres.
In the 1986 Cook County Treasurer election, incumbent third-term treasurer Edward J. Rosewell, a Democrat, was reelected.
In the 1986 President of the Cook County Board of Commissioners election, incumbent president George Dunne, a Democrat that had held the office since 1969, was reelected.
The 1986 Cook County Board of Commissioners election saw all seventeen seats of the Cook County Board of Commissioners up for election to four-year terms in two sets of elections (ten elected from an election held in the city of Chicago and seven elected from and election held in suburban Cook County).
Democrats lost a seat, and Republicans, conversely, gained a seat.
Ten seats were elected from the City of Chicago.
Republican nominee Bernard Carey was replaced on the ballot by Robert P. Gooley, as Carey opted to instead run for Illinois Attorney General, replacing James T. Ryan as the Republican nominee for that election.
In the 1986 Cook County Board of Appeals election, both seats on the board were up for election. The election was an at-large election.
One incumbent Democrat, Pat Quinn, did not seek reelection, instead running for Illinois Treasurer. The other incumbent Democrat, Harry H. Semrow, sought reelection.
In the 1986 Metropolitan Water Reclamation District of Greater Chicago election, three of the nine seats on the Metropolitan Water Reclamation District of Greater Chicago board were up for election in an at-large election. All three Democratic nominees won.
Partisan elections were held for judgeships on the Circuit Court of Cook County, due to vacancies. Other judgeships had retention elections.
Coinciding with the primaries, elections were held to elect both the Democratic and Republican committeemen for the suburban townships.