On its age, its old homes and the National Register, Olla is more historic than 17% of U.S. towns. Its share of homes from before 1940 holds the grade up; its National Register listings pull it down.
C−
HistoryA character grade: shown, never part of Olla’s overall grade.
Louisiana towns list more on the Register than most of the country (a typical Louisiana town has 3.8 per 10,000 residents, the U.S. 2.4), so Olla’s 0.0 sits below most of its state (21% of Louisiana towns have fewer) while its 0 listings outnumber those of 23% of U.S. towns.
How sure. Graded on two of the three inputs, so a change in either one moves the letter more than it would with three. The pre-1940 share is a Census survey estimate (±4.1 points).
Founding year: our sources. 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 Olla’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
The Town of Olla, incorporated in 1899 is the oldest incorporated town in LaSalle Parish and the Olla State Bank Building is the oldest permanent brick structure in LaSalle Parish. Settled prior to the American Civil War by the descendants of Scotch-Irish or Ulster Scot immigrants, the area around the modern Town of Olla was formerly known as Castor Sulfur Springs with a steamboat port located on nearby Bayou Castor. Castor Sulphur Springs was abandoned and moved to the present site of the town of Olla in 1891 when the Houston, Central Arkansas, and Northern Railroad was constructed.
Places and cemeteries from the USGS Geographic Names Information System (2021).
Questions about Olla’s history
How does Olla rank for history?
Olla is more historic than 17% 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.
How old are the homes in Olla?
5% of Olla’s homes were built before 1940 (Census estimate, ±4.1 points), against a typical 3.4% for a Louisiana town; the median home was built in 1978.
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 (2), Wikipedia 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.
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