The Rock Grove Township post office opened in 1840, the earliest record of the town by name. Another post office, Rock Grove (1840), opened inside today’s town and later closed.
2020 census: 1,473186 years
How historic is Rock Grove Township?
A−
More historic than 77% of U.S. towns, on its age, its old homes and the National Register.
Founding year: the first Rock Grove Township post office (Blevins & Helbock, CC0).
History grade
What drives Rock Grove Township’s History grade
On its age, its old homes and the National Register, Rock Grove Township is more historic than 77% of U.S. towns. All 3 inputs are above most U.S. towns; its age ranks highest and its share of homes from before 1940 lowest.
A−
HistoryA character grade: shown, never part of Rock Grove 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 Rock Grove Township’s 6.5 sits above most of its state (78% of Illinois towns have fewer) while its 1 listings outnumber those of 51% of U.S. towns.
How sure. Graded on any two of the three inputs instead, the letter would range from B+ to A−. The pre-1940 share is a Census survey estimate (±6.9 points). The founding year is the first post office, not a stated founding date.
Founding year: the first post office (other dates in Quick answers). 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 Rock Grove 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 Rock Grove Township yet. The photos, dates and memories neighbors add here are how it gets written.
Rock Grove is an unincorporated community in Stephenson County, Illinois, 6.5 miles (10.5 km) east of Orangeville. It is in Dakota Community Unit School District 201.
Its first post office opened in 1840. Between the 2010 and 2020 censuses its population grew from 1,388 to 1,473 (+6%).
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 Rock Grove Township. Tap a year, or press play to watch the town change.
1932Pecatonica 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 Rock Grove Township.
On the National Register
1 historic place in Rock Grove Township
The country’s official list of buildings and places worth saving.
The Rock Grove Township post office opened in 1840, the earliest record of the town by name (U.S. post office records).
How does Rock Grove Township rank for history?
Rock Grove Township is more historic than 77% of U.S. towns. 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.
What is on the National Register in Rock Grove Township?
One place: the Fehr, Charles, Round Barn (listed 1984).
How old are the homes in Rock Grove Township?
14% of Rock Grove Township’s homes were built before 1940 (Census estimate, ±6.9 points), against a typical 11% for an Illinois town; the median home was built in 1988.
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 the National Register of Historic Places (1), 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.
