On its age, its old homes and the National Register, Brookside Township is more historic than 34% of U.S. towns, #519 of 768 in Illinois. Its share of homes from before 1940 holds the grade up; its National Register listings pull it down.
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HistoryA character grade: shown, never part of Brookside Township’s overall grade.
Few Illinois towns list much on the Register (a typical Illinois town has 0.5 per 10,000 residents, the U.S. 2.4), so Brookside Township’s 0.0 sits below most of its state (28% of Illinois towns have fewer) while its 0 listings outnumber those of 23% of U.S. towns.
How sure. Graded on two of the three inputs, so a change in either one moves the letter more than it would with three. The pre-1940 share is a Census survey estimate (±7.1 points).
Founding year: our sources. Homes: Census ACS 2020–24. National Register: National Park Service, May 2026 list; each listing counted once (boundary changes and added documentation belong to their listing), and a historic district counts its contributing buildings. How TownRatings grades history →
What stands out about Brookside Township’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Every edition of the U.S. Geological Survey’s map of Brookside Township. Tap a year, or press play to watch the town change.
1914Centralia sheet · 1:62,500
U.S. Geological Survey historical topographic maps (public domain), via Esri’s collection of the scans. The red ring marks the center of Brookside Township.
The story so far
Brookside Township, in brief
Wikipedia doesn’t have a history of Brookside Township yet. The photos, dates and memories neighbors add here are how it gets written.
Brookside Township is one of fifteen townships in Clinton County, Illinois, United States. As of the 2020 census, its population was 4,444 and it contained 1,570 housing units. The township's name changed from Crooked Creek Township on June 1, 1874.
Between the 2010 and 2020 censuses its population fell from 5,503 to 4,444 (-19%).
Intro from Wikipedia. Population: U.S. Census Bureau.
Timeline
Brookside Township, 1835 to 1914
Woven from the archive, old maps, post office records, the National Register and the people born here.
Brookside Township is more historic than 34% of U.S. towns, #519 of 768 in Illinois. The History grade combines the town’s founding era, the share of homes built before 1940 and its National Register listings. It’s a character grade, so it isn’t part of the overall grade. How it works.
How old are the homes in Brookside Township?
13% of Brookside Township’s homes were built before 1940 (Census estimate, ±7.1 points), against a typical 11% for an Illinois town; the median home was built in 1971.
Founding dates: Wikidata, Wikipedia, the U.S. post office records of Blevins & Helbock (CC0) and the Census. Homes by year built: Census ACS 2020–24. National Register of Historic Places: National Park Service (list of May 22, 2026). Old photos, postcards and papers: Wikimedia Commons, the Library of Congress and other public archives, credited on each item’s page. Maps: U.S. Geological Survey historical topographic maps (via Esri) and Sanborn fire-insurance maps (Library of Congress). History text and census tables: Wikipedia (CC BY-SA 4.0). Places that used to be: USGS Geographic Names Information System (2021).
From U.S. Geological Survey historical maps, the US Post Offices dataset (Blevins & Helbock) and the USGS Geographic Names Information System. Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.
