From the Chicago Tribune in 1986:
Thompson-Stevenson Photo Finish Of 1982 Took Months To DevelopMy impression is that the Democrats came close to stealing the 1982 election but late in the vote count the Republicans stole it back. But I could be wrong about this. It’s pretty much forgotten history.November 05, 1986|By Dan McCaughna.
Tuesday’s contest for Illinois governor between incumbent Gov. James Thompson and Adlai Stevenson may turn out to be closer than some polls predict, but it is unlikely to equal the photofinish race the two ran against one another four years ago.
In 1982 Thompson, a Republican was re-elected to an unprecedented third term in the closest election in Illinois history. He defeated Stevenson, a former Democratic U.S. senator, by 5,074 votes out of 3,673,546 cast for governor.
Thompson's narrow victory margin of just under 0.14 of one percent probably was one of the factors that prompted Stevenson to seek a rematch this year. Stevenson's late father and namesake was a former Illinois governor and two-time Democratic presidential candidate.
Because the 1982 race was so close the outcome was not known for more than two months after the polls closed.
In fact Stevenson did not concede defeat until January, 1983, just three days before Thompson was inaugurated for his third term.
During the two months and five days between the time the polls closed on Nov. 2, 1982, and Stevenson’s concession on Jan. 7, 1983, the candidate repeatedly challenged the election outcome.
After the official canvass on Nov. 22 showed that Thompson had won, Stevenson, acting under Illinois law, demanded a recount, contending such a move would show him to be the true winner. Thompson opposed the recount as unwarranted.
Only after the Illinois Supreme Court, by a 4-3 vote, refused to order the total recount of every vote cast for governor did Stevenson admit defeat.
Oddly, few had expected a close race. Most pre-election polls showed Thompson leading by a large margin.