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A−History
History · Prairie du Sac

Prairie du Sac’s post office opened in 1839, and 18% of its homes were built before 1940

More historic than 76% of U.S. towns · #105 of 362 in Wisconsin. What drives it

Its Register listing is the Tripp Memorial Library and Hall. Below: 1 old photo or paper, maps from 1895 on, and the census since 1850.

1839first post office
1on the National Register
18%homes built before 1940
1old photo or paper
1famous people
Add an old photoShare a memory
From Prairie du Sac’s archive · credits on each photo
Quick answers

How Prairie du Sac began

When was Prairie du Sac founded?

1839

The Prairie du Sac post office opened in 1839, the earliest record of the town by name.

First census: 168 in 18502020 census: 4,420187 years

How historic is Prairie du Sac?

A−

More historic than 76% of U.S. towns, on its age, its old homes and the National Register.

What drives the grade ↓
Founding year: the first Prairie du Sac post office (Blevins & Helbock, CC0).The full story ↓
History grade

What drives Prairie du Sac’s History grade

On its age, its old homes and the National Register, Prairie du Sac is more historic than 76% of U.S. towns, #105 of 362 in Wisconsin. All 3 inputs are above most U.S. towns; its age ranks highest and its National Register listings lowest.

A−
HistoryA character grade: shown, never part of Prairie du Sac’s overall grade.
Founding era1839, from the first post office: founded 1776–1849, an older era than 75% of U.S. townsA−Homes built before 194018.1% of homes (±4.6) · typical WI town 12.1% · U.S. 8.4%B+National Register1 listing, 2.3 per 10,000 residents · typical WI town 3.0 · U.S. 2.4B
All U.S. towns we grade (21,289)Ahead of 76%
NewerOlder
Wisconsin towns of 2,500+ (362)Ahead of 71%

Wisconsin towns list more on the Register than most of the country (a typical Wisconsin town has 3.0 per 10,000 residents, the U.S. 2.4), so Prairie du Sac’s 2.3 sits near the middle of its state (60% of Wisconsin towns have fewer) while its 1 listings outnumber those of 51% of U.S. towns.

How sure. Graded on any two of the three inputs instead, the letter would range from B+ to A−. The pre-1940 share is a Census survey estimate (±4.6 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 Prairie du Sac’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 1 old photo is in the public archives. The rest are in attics and albums.On the map since 18954 editions of the USGS map, 1895 to 1974. Watch Prairie du Sac change.Deep rootsA post office since 1839: 187 years of Prairie du Sac.
★ What stands out · Help out

Start Prairie du Sac’s collection

The first neighbors to add old photos shape how Prairie du Sac’s history is told.

Decades since 1900 with photos
00s10s20s30s40s50s60s70s80s90s
0 of 10 decades. The empty ones are waiting for someone’s album.
Retake an old viewBird's eye view of Prairie du Sac, Sauk…: stand where they stood+15Share a family photoSign in to add one+10
On the map

Prairie du Sac on the map, 1895 to 1974

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

Prairie du Sac on the 1895 USGS mapPrairie du Sac on the 1908 USGS mapPrairie du Sac on the 1959 USGS mapPrairie du Sac on the 1974 USGS map1895Baraboo 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 Prairie du Sac.

Timeline

Prairie du Sac, 1839 to 1912

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

  1. 19th century
  2. 1839Post officeThe Prairie du Sac post office opens
  3. 1870In the archiveBird's eye view of Prairie du Sac, Sauk County, Wisconsin 1870
  4. 1895On the mapFirst mapped by the U.S. Geological Survey
  5. 20th century
  6. 1901Born hereJoe Schoenmann is born here
  7. 1912BuiltTripp Memorial Library and Hall is built
The story

How Prairie du Sac came to be

From Wikipedia’s history of Prairie du Sac.

Read it all →

Prairie du Sac named because the area was in the large Wisconsin River Valley where the Sauk Indians had a large settlement. Although the name of the village dates from the early days of French fur traders, Prairie du Sac was established as a village by D.B. Crocker in 1840, largely as a Yankee-English village, in contrast to its neighbor, Sauk City, which was settled largely by Germans.

The hydroelectric Prairie du Sac Dam was completed just north of the village in 1914, creating Lake Wisconsin.

Text from Wikipedia, licensed CC BY-SA 4.0.

By decade

Prairie du Sac, decade by decade

One decade in the archive so far: the 1870s. Scroll each row; tap a photo for its story.

1870s1 item
Bird's eye view of Prairie du Sac, Sauk County, Wisconsin 18701870Bird's eye view of Prairie du Sac, Sauk County, Wisco…
Today4 recent
PrairieduSacWisconsinDowntown12009PrairieduSacWisconsinDowntown1Prairie du Sac Tower north face2007Prairie du Sac Tower north facePrairieduSacsign2006PrairieduSacsignWIMap-doton-Prairie du Sac2004WIMap-doton-Prairie du Sac
Every building

Prairie du Sac, building by building, 1926

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 sheet.

Prairie du Sac fire insurance map, 1926, sheet 11926Sheet 1 of 4
BrickWoodStone

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

Then & now

Stand where they stood

No then-and-now pairs yet. Take a photo from the same spot as an old one and they appear here side by side.

Bird's eye view of Prairie du Sac, Sauk County, Wisconsin 1870
Retake this viewBird's eye view of Prairie du Sac, Sauk County, Wisconsin 1870, 1870

Find the spot, match the angle, and add your photo. It becomes the first then-and-now pair on Prairie du Sac’s page.

Retake this view · +15
On the National Register

1 historic place in Prairie du Sac

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

place listed
1
National Historic Landmarks
0
none yet
historic buildings protected
1
each building in a district counts
first listed
1981
Tripp Memorial Library and Hall
Tripp Memorial Library and Hall, built 1912
Buildings
Tripp Memorial Library and HallBuilt 1912

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

People over time

Prairie du Sac, census by census

05001,0001,5002,0002,5003,0003,5004,0004,50018501900195020004,420

Grew from 168 people in 1850 to 4,420 in 2020, more than tenfold.

16 censuses, 1850–2020.

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

Stories next door

History across the town line

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

Roxbury3 historic placesB+West PointIts storyC−Lake WisconsinIts storynot graded: under 1,000 residents or part of its town

Questions about Prairie du Sac’s history

What year was Prairie du Sac founded?

The Prairie du Sac post office opened in 1839, the earliest record of the town by name (U.S. post office records).

How does Prairie du Sac rank for history?

Prairie du Sac is more historic than 76% of U.S. towns, #105 of 362 in Wisconsin. 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 Prairie du Sac?

One place: the Tripp Memorial Library and Hall (listed 1981).

How old are the homes in Prairie du Sac?

18% of Prairie du Sac’s homes were built before 1940 (Census estimate, ±4.6 points), against a typical 12% for a Wisconsin town; the median home was built in 1990.

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 (5), Wikidata (1), the National Register of Historic Places (1), 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.