Founding year: Wikidata; Wikipedia’s history section gives the same year. First post office: 1846.The full story ↓
History grade
What drives Marengo’s History grade
On its age, its old homes and the National Register, Marengo is more historic than 84% of U.S. towns. Its share of homes from before 1940 holds the grade up; its National Register listings pull it down.
A−
HistoryA character grade: shown, never part of Marengo’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 Marengo’s 3.7 sits near the middle of its state (41% of Iowa 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 (±7.0 points). Two sources give 1845.
Founding year: Wikidata (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 Marengo’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.
Marengo was laid out in 1845 and platted in 1847. The city's name commemorates the Battle of Marengo, where Napoleon defeated the Austrian army.
The Iowa County Courthouse, built in 1893, is on the National Register of Historic Places.
In 1859, abolitionist John Brown led a group of escaped slaves from Missouri to Michigan. On February 20, the group stayed at the Draper B. Reynolds Farm 1.5 miles south of Marengo.
An explosion at the C6-Zero alternative fuel production plant resulted in a fire and multiple injuries December 2022, prompting the city to urge residents to evacuate and avoid the area until the toxic smoke cleared.
Nothing in the archives for these yearsWeddings on Main Street, storms, parades, school pictures, the old store. If it’s in your family album, it belongs here.
In 1845, according to Wikidata and Wikipedia’s history of the town. Marengo’s post office opened in 1846, and the census of 1850 counted 50 people here.
How does Marengo rank for history?
Marengo is more historic than 84% 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.
What is on the National Register in Marengo?
One place: the Iowa County Courthouse (listed 1981).
How old are the homes in Marengo?
38% of Marengo’s homes were built before 1940 (Census estimate, ±7.0 points), against a typical 22% for an Iowa town; the median home was built in 1962.
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 (3), the Library of Congress (3), 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.
1868
1939
1939
1939
