On its age, its old homes and the National Register, Olio Township is more historic than 86% of U.S. towns, #116 of 768 in Illinois. All 2 inputs are above most U.S. towns; its National Register listings ranks highest and its share of homes from before 1940 lowest.
A
HistoryA character grade: shown, never part of Olio 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 Olio Township’s 23.4 sits above most of its state (87% of Illinois towns have fewer) while its 11 historic buildings outnumber those of 76% 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 (±5.8 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 Olio Township’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Wikipedia doesn’t have a history of Olio Township yet. The photos, dates and memories neighbors add here are how it gets written.
Olio Township is located in Woodford County, Illinois. As of the 2010 census, its population was 4,931 and it contained 1,879 housing units. The largest named community in Olio Township is the city of Eureka, the Woodford County seat.
Between the 2010 and 2020 censuses its population fell from 4,931 to 4,722 (-4%).
Intro from Wikipedia. Population: U.S. Census Bureau.
By decade
No old photos in the archives yet
Weddings on Main Street, storms, parades, school pictures, the old store. If it’s in your family album, it belongs here.
Be the first to add onePhotograph a print flat, in daylight, no flash.
Every edition of the U.S. Geological Survey’s map of Olio Township. Tap a year, or press play to watch the town change.
1927Danvers 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 Olio Township.
On the National Register
2 listings protect 11 historic buildings
The country’s official list of buildings and places worth saving.
places listed
2
National Historic Landmarks
0
none yet
historic buildings protected
11
each building in a district counts
National Park Service, National Register of Historic Places. Photos from Wikimedia Commons, credited on each place’s page.
Famous people
Famous people close to Olio Township
Nobody well known was born in Olio Township itself, so here are the best known from just nearby.
Olio Township is more historic than 86% of U.S. towns, #116 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 Olio Township?
18% of Olio Township’s homes were built before 1940 (Census estimate, ±5.8 points), against a typical 11% for an Illinois town; the median home was built in 1962.
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 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.
