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A+History
History · Delavan

Delavan’s post office opened in 1840, and 38% of its homes were built before 1940

More historic than 96% of U.S. towns. What drives it

3 places in town are on the National Register, among them a historic district with 20 buildings. Below: maps from 1888 on and the census since 1880.

1840first post office
3on the National Register
38%homes built before 1940
3famous people
Quick answers

How Delavan began

When was Delavan founded?

1840

The Delavan post office opened in 1840, the earliest record of the town by name.

First census: 1,340 in 18802020 census: 1,568186 years

How historic is Delavan?

A+

More historic than 96% of U.S. towns, on its age, its old homes and the National Register.

What drives the grade ↓
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.
All U.S. towns we grade (21,289)Ahead of 96%
NewerOlder

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.

★ What stands out · Help out

Start Delavan’s collection

The first neighbors to add old photos shape how Delavan’s history is told.

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.
On the National Register

3 listings protect 21 historic buildings

The country’s official list of buildings and places worth saving.

places listed
3
National Historic Landmarks
0
none yet
historic buildings protected
21
each building in a district counts
first listed
1991
Delavan Commercial Historic District
BuildingsDistrictsStructures

Architectural styles listings

Commercial1
Italianate1
Queen Anne1
Classical Revival1
Double intersection Warren pony truss.1

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 fire insurance map, 1888, sheet 11888Sheet 1 of 3
Edition
BrickWoodStone

Sanborn Map Company, via the Library of Congress. Editions published in 1930 or earlier, which are in the public domain.

The story

How Delavan came to be

From Wikipedia’s history of Delavan.

Read it all →

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.

Text from Wikipedia, licensed CC BY-SA 4.0.

Timeline

Delavan, 1840 to 1942

Woven from the archive, old maps, post office records, the National Register and the people born here.

  1. 19th century
  2. 1840Post officeThe Delavan post office opens
  3. 1891Born hereJohn T. Culbertson, Jr. is born here
  4. 1896Born hereJulia Thecla is born here
  5. 20th century
  6. 1914BuiltAyer Public Library is built
  7. 1915Born hereJohnny McDowell is born here
  8. 1942On the mapFirst mapped by the U.S. Geological Survey
By decade

Delavan, decade by decade

On the map

Delavan on the map in 1942

The U.S. Geological Survey’s map of Delavan.

Delavan on the 1942 USGS map1942Delavan 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 Delavan.

People over time

Delavan, census by census

05001,0001,5002,00018801900192019401960198020002020Peak: 1,973

Between 1,084 and 1,973 people in every census since 1880.

15 censuses, 1880–2020.

U.S. Census Bureau decennial counts, from the census table on Delavan’s Wikipedia page.

Famous people

3 famous people were born in Delavan

Writers, athletes, leaders and more, ranked by how widely they’re known.

See all →

Questions about Delavan’s history

What year was Delavan founded?

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.

Memory lane

What the archives can’t tell you, neighbors can.

Town Square →
Start a conversation
Sources

Where this page comes from

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.