Founding year: the first Delavan post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Delavan’s History grade
On its age, its old homes and the National Register, Delavan is more historic than 96% of U.S. towns. All 3 inputs are above most U.S. towns; its share of homes from before 1940 ranks highest and its age lowest.
A+
HistoryA character grade: shown, never part of Delavan’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 Delavan’s 141 sits above most of its state (95% of Illinois towns have fewer) while its 21 historic buildings outnumber those of 80% 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 (±6.5 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 Delavan’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
National Park Service, National Register of Historic Places. Photos from Wikimedia Commons, credited on each place’s page.
Every building
Delavan, building by building, 1888–1906
Fire insurance maps drew every building, what it was made of and what it was used for, so insurers could price the risk of fire. Pick a year, then a sheet.
Delavan was founded by a group of settlers from Rhode Island. The city derives its name from Edward C. Delavan, a temperance advocate from Albany, New York. A post office has been in operation at Delavan since 1840.
The Delavan post office opened in 1840, the earliest record of the town by name (U.S. post office records).
How does Delavan rank for history?
Delavan is more historic than 96% 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 Delavan?
Three places: the Delavan Commercial Historic District (listed 1991), the Ayer Public Library (1998) and the Third St. Bridge (1999).
How old are the homes in Delavan?
38% of Delavan’s homes were built before 1940 (Census estimate, ±6.5 points), against a typical 11% for an Illinois town; the median home was built in 1955.
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 Wikimedia Commons (2), Wikidata (3), the National Register of Historic Places (3), Wikipedia, Wikidata and Wikipedia for famous people, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), the US Post Offices dataset (Blevins & Helbock), the USGS Geographic Names Information System and Sanborn fire insurance maps (Library of Congress). Archive images are copied here with their credits and licenses, shown on each photo’s page. Refreshed monthly.