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History · Somonauk Township

Somonauk Township’s post office opened in 1836, and 32% of its homes were built before 1940

Below: 3 old photos and papers, maps from 1948 on, and the census since 1880.

1836first post office
0on the National Register
32%homes built before 1940
3old photos & papers
Add an old photoShare a memory
From Somonauk Township’s archive · credits on each photo
Quick answers

How Somonauk Township began

When was Somonauk Township founded?

1836

The Somonauk Township post office opened in 1836, the earliest record of the town by name. Another post office, Franks (1891), opened inside today’s town and later closed.

First census: 587 in 18802020 census: 2,006190 years
Founding year: the first Somonauk Township post office (Blevins & Helbock, CC0).The full story ↓

What stands out about Somonauk 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 writtenOnly 3 old photos are in the public archives. The rest are in attics and albums.Deep rootsA post office since 1836: 190 years of Somonauk Township.
★ What stands out · Help out

Start Somonauk Township’s collection

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

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
1 of 10 decades. The empty ones are waiting for someone’s album.
Retake an old view19960720 05 BNSF near Somonauk, IL: stand where they stood+15Share a family photoSign in to add one+10
Timeline

Somonauk Township, 1891 to 1996

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

  1. 19th century
  2. 1891Post officeThe Franks post office opens
  3. 20th century
  4. 1902Post officeThe Franks post office closes
  5. 1948On the mapFirst mapped by the U.S. Geological Survey
  6. 1996In the archive19960720 05 BNSF near Somonauk, IL
The story

How Somonauk Township came to be

From Wikipedia’s history of Somonauk Township.

Read it all →

The name "Somonauk" is of Pottawatomie origin. The name is most likely derived from the phonetic phrase As-sim-in-eh-kon, which translates to "pawpaw grove", in reference to the vast groves of pawpaw trees that filled the area at that time.

Text from Wikipedia, licensed CC BY-SA 4.0.

By decade

Somonauk Township, decade by decade

One decade in the archive so far: the 1990s. Scroll each row; tap a photo for its story.

1990s3 items
19960720 05 BNSF near Somonauk, IL199619960720 05 BNSF near Somonauk, IL19960720 06 BNSF near Sandwich, IL199619960720 06 BNSF near Sandwich, IL19960720 07 BNSF Somonauk, IL199619960720 07 BNSF Somonauk, IL
Today1 recent
20140119 02 BNSF Somonauk, Illinois201420140119 02 BNSF Somonauk, Illinois
On the map

Somonauk Township on the map, 1948 to 1971

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

Somonauk Township on the 1948 USGS mapSomonauk Township on the 1950 USGS mapSomonauk Township on the 1971 USGS map1948Sandwich 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 Somonauk Township.

People over time

Somonauk Township, census by census

05001,0001,5002,00018801900192019401960198020002020Peak: 1,893

Between 468 and 1,893 people in every census since 1880.

15 censuses, 1880–2020.

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

Places that used to be

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

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

Hamlets and corners on the map
Franks
Gone or out of use
Coleman SchoolschoolHays SchoolschoolSomonauk SchoolschoolWarren Landing Stripairport
3cemeteries and burying grounds inside Somonauk Township
Oak MoundOak RidgeVan Olindas

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.

Sandwich Township2 historic placesnot graded: under 1,000 residents or part of its townNorthville TownshipIts storyCVictor TownshipIts storynot graded: under 1,000 residents or part of its town

Questions about Somonauk Township’s history

What year was Somonauk Township founded?

The Somonauk Township post office opened in 1836, the earliest record of the town by name (U.S. post office records).

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). How TownRatings grades history →

From Wikimedia Commons (4), 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.