With roughly 3.5 million votes cast — meaning 1 percentage point is 35,000 votes — that’s a margin of .014 percent.

Barring a 10-fold increase in that margin between now and Nov. 18 — the deadline for vote-counting by county clerks and other local election authorities — the 2014 treasurer’s contest is all but certain to become the closest statewide election in Illinois in at least the last 50 years. It’s likely that it could be the closest statewide race in Illinois history.

I say “likely” because there’s no official (or unofficial) historic, comparative tally of of statewide election victory margins. We know from memory that the 2010 gubernatorial election between Pat Quinn and Bill Brady was pretty darn close.  Those of voting age 32 years ago may even remember the 1982 race between Jim Thompson and Adlai Stevenson, which was even closer.

With an Excel spreadsheet, it’s easy to download and sort election results from 1998 forward. That’s when the Illinois State Board of Elections began maintaining easily accessible election results on its website. For pre-1998 elections, the only way to compare closeness in statewide elections — meaning state constitutional offices and U.S. Senate — is to sift through paper records.

Which is what I did for all statewide elections going back to 1964. I had grand ambitions of compiling 100 years of election results, but 50 years’ worth of manual data entry proved a sufficient test of my threshold of tedium. (Note to college political science students in need of a project: If you’d like to continue this process going back to 1818, I will be happy to publish your results!)

With a margin of victory of .14 percent, the Thompson-Stevenson race of 1982 is by far the closest of the last 50 years. The next closest, the Quinn-Brady race four years ago, had a margin of victory six times greater. Those are the only two contests of the last 50 years in which margins of victory were less than 1 percent.

A few interesting footnotes on the chart below:

When Paul Simon defeated Republican Paul Dwyer in the 1968 lieutenant governor’s race by 2.2 percentage points (96,000 votes), it set up a two-party gubernatorial administration in which Democrat Simon was next-in-command to Republican Gov Richard Ogilvie. That set up a change in state law in which the winning lieutenant governor candidate in each party’s primary was paired with the respective gubernatorial candidate. Beginning with this year’s election, the governor and lieutenant governor candidates ran together as running mates in both primary and general elections.

After narrowly losing to Thompson in 1982, Stevenson again challenged Thompson in 1986. That contest was not a nail-biter, with Thompson defeating Stevenson by 13 percentage points (just shy of 400,000 votes).

With political talk now turning to the 2016 U.S. Senate and the Republicans’ challenge to hold their new majority, there’s a lot of chatter about Illinois Democrats mounting a challenge to Mark Kirk. A look at Kirk’s 2010 margin of victory is a reminder of why this race easily could be competitive with the right candidate.

Also worth noting is that the 10 races here are the only contests going back to 1964 with margins of victory of less than 100,000 votes.

NEXT ARTICLE Devil’s Advocate on 2014 Illinois election: Nice job, voters. Do you know what you just did?

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  5.  2014 Illinois governor’s race smashes records for campaign spendingMatthew Dietrich is Reboot’s executive editor. An award-winning journalist, Dietrich is the former editorial page editor of the State Journal Register in Springfield. He believes in holding our politicians accountable. Read Dietrich’s take on the leadership vacuum that sent Illinois sinking. You can find Reboot on Facebook and on Twitter @rebootillinois.