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A−History
History · Hennepin Township

Hennepin Township’s post office opened in 1831, and 18% of its homes were built before 1940

More historic than 83% of U.S. towns. What drives it

2 places in town are on the National Register. Below: maps from 1893 on and the census since 1880.

1831first post office
2on the National Register
18%homes built before 1940
Add an old photoShare a memory
Photo: Nyttend · Public domain
Quick answers

How Hennepin Township began

When was Hennepin Township founded?

1831

The Hennepin Township post office opened in 1831, the earliest record of the town by name. Wikidata gives 1837. Another post office, Florid (1849), opened inside today’s town and later closed.

First census: 623 in 18802020 census: 1,223195 years

How historic is Hennepin Township?

A−

More historic than 83% of U.S. towns, on its age, its old homes and the National Register.

What drives the grade ↓
Founding year: the first Hennepin Township post office (Blevins & Helbock, CC0). Wikidata: 1837.The full story ↓
History grade

What drives Hennepin Township’s History grade

On its age, its old homes and the National Register, Hennepin Township is more historic than 83% 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 Hennepin Township’s overall grade.
Founding era1831, from the first post office: founded 1776–1849, an older era than 75% of U.S. townsA−Homes built before 194018.0% of homes (±4.9) · typical IL town 10.6% · U.S. 8.4%B+National Register2 listings, 13.9 per 10,000 residents · typical IL town 0.5 · U.S. 2.4B+
All U.S. towns we grade (21,289)Ahead of 83%
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 Hennepin Township’s 13.9 sits above most of its state (85% of Illinois towns have fewer) while its 2 listings outnumber those of 60% of U.S. towns.

How sure. Graded on any two of the three inputs instead, the letter would still be A−. The pre-1940 share is a Census survey estimate (±4.9 points). The founding year is the first post office, not a stated founding date; Wikidata’s 1837 falls in the same era, so the grade doesn’t depend on which one is used.

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 Hennepin Township’s past

Read from the archive, the National Register and the record. The page puts what stands out first.

A history waiting to be writtenNo old photos of Hennepin Township are in the public archives yet. The rest are in attics and albums.Shrank, then grewLost half of its people between 1880 and 1930, then more than doubled.On the map since 18933 editions of the USGS map, 1893 to 1972. Watch Hennepin Township change.Deep rootsA post office since 1831: 195 years of Hennepin Township.
★ What stands out · Help out

Start Hennepin Township’s collection

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

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.
Share a family photoSign in to add one+10
People over time

Hennepin Township, census by census

020040060080018801900192019401960198020002020623 in 1880Low: 312

Lost half of its people between 1880 and 1930, then more than doubled.

15 censuses, 1880–2020.

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

On the map

Hennepin Township on the map, 1893 to 1972

Every edition of the U.S. Geological Survey’s map of Hennepin Township. Tap a year, or press play to watch the town change.

Hennepin Township on the 1893 USGS mapHennepin Township on the 1933 USGS mapHennepin Township on the 1972 USGS map1893Lacon 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 Hennepin Township.

The story

How Hennepin Township came to be

From Wikipedia’s history of Hennepin Township.

Read it all →

The Village of Hennepin was named for the explorer, Louis Hennepin.

The Putnam County Courthouse, in Hennepin, was built in 1837, and is the oldest county courthouse in Illinois still serving its original purpose. Abraham Lincoln visited the courthouse, including when he campaigned for a Congressional seat in September 1845. The Putnam County Courthouse is listed on the National Register of Historic Places.

Text from Wikipedia, licensed CC BY-SA 4.0.

Timeline

Hennepin Township, 1849 to 2020

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

  1. 19th century
  2. 1849Post officeThe Florid post office opens
  3. 1893On the mapFirst mapped by the U.S. Geological Survey
  4. 20th century
  5. 1907Post officeThe Florid post office closes
  6. 21st century
  7. 2020CensusPopulation peaks at 769
By decade

Hennepin Township, decade by decade

Today4 recent
Putnam County Courthouse, Hennepin2014Putnam County Courthouse, HennepinInterstate 180, Hennepin, Illinois2013Interstate 180, Hennepin, IllinoisHennepin, Illinois2013Hennepin, IllinoisHennepin, Illinois2012Hennepin, Illinois
On the National Register

2 historic places in Hennepin Township

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

places listed
2
National Historic Landmarks
0
none yet
historic buildings protected
2
each building in a district counts

National Park Service, National Register of Historic Places. Photos from Wikimedia Commons, credited on each place’s page.

Places that used to be

Lost post offices, old corners, places now gone and burying grounds

Another post office, Florid, opened and closed inside today’s town.

Hamlets and corners on the map
FloridMoronts
Gone or out of use
Maple Grove SchoolschoolPoole SchoolschoolPutnam County FarmlocaleSand Prairie SchoolschoolStrawn SchoolschoolWindblown Bottoms Duck Clublocale
3cemeteries and burying grounds inside Hennepin Township
FloridFloridUnion Grove

US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).

Stories next door

History across the town line

Each neighbor’s History grade, on the same three inputs.

Senachwine Township1 historic placenot graded: under 1,000 residents or part of its townLeepertown TownshipIts storynot graded: under 1,000 residents or part of its townHennepin2 historic placesnot graded: under 1,000 residents or part of its townGranville TownshipIts storyB+Magnolia TownshipIts storyB+Henry TownshipIts storynot graded: under 1,000 residents or part of its town

Questions about Hennepin Township’s history

What year was Hennepin Township founded?

The Hennepin Township post office opened in 1831, the earliest record of the town by name (U.S. post office records). Wikidata gives 1837.

How does Hennepin Township rank for history?

Hennepin Township is more historic than 83% 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.

How old are the homes in Hennepin Township?

18% of Hennepin Township’s homes were built before 1940 (Census estimate, ±4.9 points), against a typical 11% for an Illinois town; the median home was built in 1976.

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 (4), Wikidata (2), Wikipedia, U.S. Geological Survey historical maps, U.S. Census counts (via Wikipedia), 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.