The Osage post office opened in 1856, the earliest record of the town by name. Another post office, Cora (1855), opened inside today’s city and later closed.
First census: 1,400 in 18702020 census: 3,627170 years
How historic is Osage?
A−
More historic than 81% of U.S. towns, on its age, its old homes and the National Register.
Founding year: the first Osage post office (Blevins & Helbock, CC0).The full story ↓
History grade
What drives Osage’s History grade
On its age, its old homes and the National Register, Osage is more historic than 81% of U.S. towns, #47 of 140 in Iowa. Its National Register listings hold the grade up; its age pulls it down.
A−
HistoryA character grade: shown, never part of Osage’s overall grade.
Iowa towns list more on the Register than most of the country (a typical Iowa town has 9.1 per 10,000 residents, the U.S. 2.4), so Osage’s 140 sits above most of its state (87% of Iowa towns have fewer) while its 50 historic buildings outnumber those of 85% 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 (±6.7 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 Osage’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
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.
The first plat of the town was started in 1854 by a Dr. Moore and named after his eldest daughter “Cora”, but the name was never recorded. In 1855 a Mr. Gibbs arrived from Massachusetts, representing wealthy capitalists in Massachusetts and Connecticut. He prevailed upon Mr. Orrin Sage, a great banker from Ware, MA to invest in this community, and later Mr. Sage gave $2,000 and 600 acres of land to the Library Building Fund. Because of his benevolence, the town’s name was changed to Osage in his honor.
Osage’s post office has been open since 1856. Another post office, Cora, opened and closed inside today’s town.
Cora
1855–1856
Osage
1856–today
18501940today
Gone or out of use
Cedar Valley Seminaryschool
US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).
Questions about Osage’s history
What year was Osage founded?
The Osage post office opened in 1856, the earliest record of the town by name (U.S. post office records).
How does Osage rank for history?
Osage is more historic than 81% of U.S. towns, #47 of 140 in Iowa. 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 Osage?
5 listings: 4 buildings, among them the Mitchell County Courthouse (listed 1977, the first), and 1 historic district, the Osage Commercial Historic District, with 46 contributing buildings. 50 historic buildings in all.
How old are the homes in Osage?
30% of Osage’s homes were built before 1940 (Census estimate, ±6.7 points), against a typical 22% for an Iowa town; the median home was built in 1965.
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 (2), the National Register of Historic Places (5), 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.
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