Look at an Illinois county political map and you'll see a sea of red. It's overwhelming. From the Wisconsin border down to Cairo, where the Ohio and Mississippi rivers meet, the state looks like a Republican stronghold.
But then you check the actual election results. Democrats win statewide by double digits. Year after year.
It’s the classic "land doesn't vote, people do" dilemma, but in Illinois, it's amplified to an extreme degree. Honestly, if you only saw the map without the population data, you’d swear you were looking at Nebraska.
The Massive Blue Anchor in the Northeast
Basically, the entire political gravity of Illinois sits in Cook County. It's the home of Chicago, and it holds about 40% of the state's entire population. In the 2024 election, Kamala Harris took about 70.4% of the vote there. That’s a massive surplus of blue votes that most of the other 101 counties just can't offset.
But the "Collar Counties" are where the real story is. For decades, places like DuPage, Lake, and Will were the "Republican Wall." They were wealthy, suburban, and reliably conservative. That’s just not the case anymore.
- DuPage County: Once the crown jewel of Illinois Republicanism, it went for Harris with 55.9% of the vote.
- Lake County: This one wasn't even close, with a 21-point margin for the Democrats.
- Will and Kane: Both stayed blue, though Will was a tight 50.1% to 48.5% split.
When you lose the suburbs, you lose the state. It's that simple.
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The Red Shift Nobody is Talking About
While the state stayed blue in 2024, the Illinois county political map actually showed a significant rightward shift. Harris won by about 11 points. Sounds like a lot, right? Well, Joe Biden won it by 17 points in 2020.
That’s a 6-point swing.
Where did it come from? Lower turnout in Chicago was a huge factor. Harris received roughly 300,000 fewer votes in Cook County than Biden did. Meanwhile, Donald Trump actually improved his raw vote totals in Chicago and the surrounding areas.
Surprising Red Pockets
Even in the north, the "red" is creeping back into the suburbs. McHenry County went for Trump by about 5 points. Sangamon County, home to the state capital of Springfield, also stayed in the Republican column with a 5-point margin.
Further south, the margins become eye-popping. In Effingham County, Trump pulled over 79% of the vote. In Fayette County, it was over 81%. These aren't just "leaning" red; they are deep, deep crimson.
The "Two Illinois" Problem
There’s a growing movement in the southern part of the state to basically "secede" from Cook County. You've probably heard of it. Several counties have actually passed non-binding referendums to explore forming a new state.
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It's born out of a feeling that Chicago-centric policies—on guns, taxes, and energy—don't fit the lifestyle of someone living in Saline or Iroquois county.
"The interests of downstate communities and Chicago are often aligned on things like school funding, yet the political rhetoric treats them like different planets." — Analysis from the Center for Tax and Budget Accountability.
The map reinforces this "us vs. them" mentality. When 90+ counties are red and the state still votes blue, people in those red counties feel like their voices are being drowned out by a single city.
The Pivot Counties: Where the Swing Happens
Illinois has a handful of "Pivot Counties"—places that voted for Obama twice and then flipped to Trump.
- Knox County: This used to be a reliable bellwether. In 2024, it went for Trump by 9 points.
- Whiteside and Henry: These industrial-leaning counties in the northwest have stayed red since the 2016 realignment.
- Winnebago (Rockford): This is one of the few urban centers that actually stayed blue, but only by a razor-thin 1-point margin.
If Republicans want to win statewide again, they have to claw back the "Collar Counties" while keeping these pivot counties deep red. Right now, they’re doing the latter, but failing at the former.
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What to Watch for in 2026
We're heading into a midterm cycle where the Illinois county political map will be tested again. The big question is whether the "red shift" we saw in 2024 was a one-time thing or a permanent trend.
- Voter Turnout: If Chicago turnout stays low, the statewide margins will keep shrinking.
- The Suburbs: Can Republicans make inroads in DuPage and Kendall again?
- Economic Issues: Downstate voters are primarily motivated by the economy and energy costs.
If you’re looking to understand the real politics of the Prairie State, don't just look at the colors on the map. Look at the margins in the suburbs. That’s where the power actually sits.
To get a better handle on these shifts, you should pull the raw data from the Illinois State Board of Elections website. They provide precinct-level data that shows exactly which neighborhoods are changing. Also, keep an eye on the Cook Political Report for 2026 House race ratings, as those often signal which way the suburban wind is blowing before the big maps are drawn.