Lake County, Illinois
county in Illinois, United States
Lake County is a county located in the northeastern corner of the U.S. state of Illinois, along the shores of Lake Michigan. As of the 2020 census, it has a population of 714,342, making it the third-most populous county in Illinois. Its county seat is Waukegan, the tenth-largest city in Illinois. The county is a mixture of suburban areas, urban areas, and some rural areas. Due to its location, immediately north of Cook County, Lake County is one of the collar counties of the Chicago metropolitan area. Its northern boundary is the Wisconsin state line.
According to the 2010 census, Lake County is the second wealthiest county in the state by per capita income, after DuPage County. Additionally, Lake County ranks as the 27th wealthiest county in the nation. The county includes the affluent North Shore communities of Lake Forest, Lake Bluff, and Highland Park, and much of the county's wealth is concentrated in this area, as well as in communities bordering Cook County to the south and McHenry County to the west. The north and northwest areas of the county, though historically rural and exurban, have experienced rapid suburbanization in the past three decades, while the lakefront communities of Waukegan, North Chicago, and Zion are postindustrial areas that have majority-minority populations.
Begin with the source’s own compact description: “Lake County, Illinois” is county in Illinois, United States. The dossier treats that line as a proposition to test through Lake, County and Illinois, not as a finished interpretation.
Why this record matters
The phrase “county in Illinois, United States” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Maps, plans, fabric surveys and administrative records can establish how the site’s name, extent and function changed over time. The source revision retrieved here is dated Sep 16, 2026. The linked authority identifier is Q484263. The first chronological checks are 2020 and 2010.
Modern boundaries and familiar names can conceal earlier jurisdictions or structures that do not align with the present site. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
- Historic place names
- Jurisdictional context
- Routes into maps and plans
Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
- Establish the record: confirm the title “Lake County, Illinois”, its source revision and the description used here.
- Expand the search: follow Lake County, Illinois primary sources, Lake County, Illinois archive and Lake research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Lake County, Illinois”?
- Which earlier names or jurisdictions may reveal additional records?
- Which authority defined the place, boundary or structure at the relevant date?
Search terms from this dossier
This entry incorporates text from “Lake County, Illinois” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.