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Al's Oasis summer 2016 02Photo: Runner1928 · CC BY-SA 4.0
–Not graded
History · Oacoma Township

Oacoma Township dates to 1891

Most of Oacoma Township was built recently: 0.0% of its homes predate 1940 and the median home dates from 2006. Below: maps from 1935 on and the census since 1910.

1891founded
0on the National Register
0.0%homes built before 1940
Add an old photoShare a memory
Photo: Runner1928 · CC BY-SA 4.0
Quick answers

How Oacoma Township began

When was Oacoma Township founded?

1891

Oacoma Township dates its founding to 1891 (Wikipedia’s history). The census first counted it in 1910.

First census: 235 in 19102020 census: 70135 years
Founding year: Wikipedia. First post office: 1890.The full story ↓

What stands out about Oacoma 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 Oacoma Township are in the public archives yet. The rest are in attics and albums.Lost villages2 post offices opened and closed inside today’s Oacoma Township.
★ What stands out · Help out

Start Oacoma Township’s collection

The first neighbors to add old photos shape how Oacoma 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
Places that used to be

Lost post offices, places now gone and burying grounds

Two other post offices opened and closed inside today’s town.

Lyman
1890–1964
Fort Lookout
1919–1943
18901960today
Gone or out of use
Fort LookoutlocaleLower Brule AgencylocaleLyman Post Officepost officeMedicine Bulls Camplocale
1cemetery inside Oacoma Township
Moeller

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

The story

How Oacoma Township came to be

From Wikipedia’s history of Oacoma Township.

Read it all →

On September 17, 1804, Lewis and Clark camped on the west bank of the Missouri River near American Island where Oacoma is now located. During the remainder of the 19th century the area was a stopping off place for explorers, fur traders and steamboat men. The township of Oacoma was laid out in 1891 as the county seat for the newly formed Lyman County; the County seat was transferred to the town of Kennebec in 1922. The Chicago, Milwaukee, St. Paul and Pacific Railroad arrived in Oacoma in 1905, and Oacoma was known as a "banking post-village". In the 21st century, it is a rest stop for travelers on Interstate 90.

Text from Wikipedia, licensed CC BY-SA 4.0.

Timeline

Oacoma Township, 1890 to 1964

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

  1. 19th century
  2. 1890Post officeThe Lyman post office opens
  3. 1891
    FoundingOacoma Township is established
  4. 20th century
  5. 1919Post officeThe Fort Lookout post office opens
  6. 1935On the mapFirst mapped by the U.S. Geological Survey
  7. 1943Post officeThe Fort Lookout post office closes
  8. 1964Post officeThe Lyman post office closes
By decade

Oacoma Township, decade by decade

Today7 recent
Oacoma SD water tower2016Oacoma SD water towerI-90 Business Loop bridge across Missouri River2014I-90 Business Loop bridge across Missouri RiverBecket Mass Sign2014Becket Mass SignErosion control blocks of Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga; Interstate 90 at the Missouri River2012Erosion control blocks of Sioux Quartzite (Paleoprote…Al's Oasis2009Al's OasisMotorcycle rider next to Missouri River between Chamberlain and2007Motorcycle rider next to Missouri River between Chamb…SDMap-doton-Oacoma2004SDMap-doton-Oacoma
On the map

Oacoma Township on the map, 1935 to 1952

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

Oacoma Township on the 1935 USGS mapOacoma Township on the 1952 USGS map1935Chamberlain 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 Oacoma Township.

People over time

Oacoma Township, census by census

0100200300400500192019401960198020002020Peak: 451

Between 167 and 451 people in every census since 1910.

12 censuses, 1910–2020.

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

Stories next door

History across the town line

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

Iona TownshipIts storynot graded: under 1,000 residents or part of its townOacomaIts storynot graded: under 1,000 residents or part of its townBrule TownshipIts storynot graded: under 1,000 residents or part of its townWest Point TownshipIts storynot graded: under 1,000 residents or part of its townChamberlain Township1 historic placenot graded: under 1,000 residents or part of its town

Questions about Oacoma Township’s history

What year was Oacoma Township founded?

In 1891, according to Wikipedia’s history of the town. Oacoma Township’s post office opened in 1890, and the census of 1910 counted 235 people here.

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 (7), 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.