The Dorr Township post office opened in 1845, the earliest record of the town by name. Two smaller post offices, Dorr (1845) and Ridgefield (1858), opened inside today’s town and later closed.
2020 census: 21,572181 years
How historic is Dorr Township?
A
More historic than 91% of U.S. towns, on its age, its old homes and the National Register.
Founding year: the first Dorr Township post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Dorr Township’s History grade
On its age, its old homes and the National Register, Dorr Township is more historic than 91% of U.S. towns, #63 of 768 in Illinois. All 3 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 Dorr 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 Dorr Township’s 32.8 sits above most of its state (89% of Illinois towns have fewer) while its 71 historic buildings outnumber those of 87% of U.S. towns.
How sure. Graded on any two of the three inputs instead, the letter would range from A− to A. The pre-1940 share is a Census survey estimate (±3.2 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 Dorr Township’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Dorr Township is named after Governor Thomas Wilson Dorr of Rhode Island. Governor Dorr helped to modernize voting in America by removing arcane age limitations and fighting for universal white male suffrage. Dorr was arrested and tried for treason before the Rhode Island Supreme Court. In 1844 he was committed to prison with a life sentence of solitary confinement and hard labor. He was released after 12 months but his health never fully recovered.
Every edition of the U.S. Geological Survey’s map of Dorr Township. Tap a year, or press play to watch the town change.
1926McHenry 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 Dorr Township.
On the National Register
2 listings protect 71 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
71
each building in a district counts
National Park Service, National Register of Historic Places. Photos from Wikimedia Commons, credited on each place’s page.
Stories next door
History across the town line
Each neighbor’s History grade, on the same three inputs.
The Dorr Township post office opened in 1845, the earliest record of the town by name (U.S. post office records).
How does Dorr Township rank for history?
Dorr Township is more historic than 91% of U.S. towns, #63 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 Dorr Township?
20% of Dorr Township’s homes were built before 1940 (Census estimate, ±3.2 points), against a typical 11% for an Illinois town; the median home was built in 1983.
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 Wikipedia, 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.
