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Fact check: Which counties in Illinois have the highest percentage of Democratic voters?
Executive Summary
Illinois’s strongest Democratic concentrations are centered in the Chicago metropolitan area, with Cook County and adjacent suburban counties (DuPage, Lake, Kane, Will) repeatedly delivering the highest Democratic vote shares in recent presidential contests; Cook County is repeatedly identified as the single most Democratic county by vote percentage [1] [2] [3]. Statewide results confirm Illinois as a blue state, but the data available do not provide a complete ranked list of every county by Democratic share; analyses instead rely on county-by-county returns from 2020 and 2024 to show the pattern that urban Cook and nearby collar counties are the dominant Democratic strongholds while many central and southern counties lean Republican [2] [4] [3].
1. What claim the materials make and why it matters—The Midwest blue pocket that decides Illinois
The provided materials repeatedly claim that Illinois’s Democratic strength is concentrated in the Chicago metro area, with Cook County producing the largest Democratic margins and the suburban collar counties providing substantial Democratic votes that keep the state reliably blue; this is stated in county-result summaries for 2024 and in 2020 mapping exercises [1] [2] [4]. The claim matters because statewide outcomes are driven by population-weighted urban centers, not by county counts, and the sources highlight Cook County’s decisive size and vote share as the principal reason Illinois votes Democratic in presidential years [1] [3]. Several reports explicitly point to DuPage, Lake, Kane and Will as Democratic in 2024, reinforcing the pattern from 2020 maps that the Chicago region concentrates Democratic voters [2] [5].
2. What the recent sources actually show—County wins, vote shares, and mapping signals
Recent articles and the county-by-county 2024 breakdown show Kamala Harris winning Illinois with roughly mid-50 percent shares statewide and Cook County posting substantially higher Democratic percentages—one report cites a Cook County vote share near 69.6% for the Democratic ticket in 2024 [1] [3]. News mapping from 2020 and 2024 provides visual confirmation that northern Illinois and the Chicago suburbs are the darkest-blue areas on county maps, while central and southern counties tilt Republican; multiple sources summarize county winners but stop short of publishing a single authoritative ranked table of Democratic percentages for every county [5] [6] [7]. The available sources therefore allow confident identification of top Democratic counties by pattern and by specific callouts (Cook and major collar counties) but not a fully enumerated statewide rank in the provided material [2] [3].
3. Reconciling apparent discrepancies—Why different pieces emphasize different counties
Some sources emphasize Cook County’s overwhelming Democratic vote count while others highlight multiple suburban counties that voted Democratic in 2024; this is not a contradiction but a difference in emphasis and granularity. The 2024 county breakdowns list Cook as the largest and most Democratic county by percentage in the state, and separate reporting names DuPage, Kane, Lake and Will among counties that also favored the Democratic ticket [1] [2] [3]. Mapping sources from 2020 show the same geographic pattern but with color-coded vote-share intensity rather than explicit percentage rankings, which can create the impression of inconsistent claims when the underlying data are actually aligned: Cook County leads by Democratic percent, with adjacent collar counties forming a secondary cluster of high Democratic support [5] [6].
4. Limits in the provided evidence and important omitted considerations
The assembled material lacks a single, up-to-date tabulation that lists every Illinois county by Democratic percentage, and several entries explicitly note that specific county percentage ranks are not provided in the articles [1] [2] [8]. The sources are focused on election outcomes (winners and maps) rather than a comprehensive demographic or registration-based ranking of partisan percentage by county, so registration figures, turnout differences, and year-to-year shifts are not fully captured in the supplied analyses [4] [7]. For a definitive ranked list one would need the official county-by-county certified returns or a compiled dataset that lists Democratic vote percentage for each county in the most recent election, which the current materials reference indirectly but do not publish in complete form [3] [5].
5. Bottom line and practical takeaways for readers seeking precise rankings
The consistent, corroborated finding across the sources is that Cook County is the most Democratic county in Illinois by vote share, and the Chicago-area collar counties—DuPage, Lake, Kane and Will—are the next strongest Democratic counties; central and southern Illinois counties generally vote Republican [1] [2] [5] [3]. The provided reporting and maps confirm this geographic concentration but do not include a full ranked table of Democratic percentages for all 102 counties; obtaining that precise ranking requires consulting certified county vote returns or a compiled dataset derived from official returns, which the current sources summarize but do not exhaustively list [6] [4].