The Clyde Park post office opened in 1887, the earliest record of the town by name. Another post office, Sunnyside (1885), opened inside today’s town and later closed.
2020 census: 332139 years
Founding year: the first Clyde Park post office (Blevins & Helbock, CC0).The full story ↓
What stands out about Clyde Park’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Founded in the 1870s, the present-day site of Clyde Park was founded as Sunnyside by Texas cattlemen who were attracted to the area for grazing their herds. The post office in Sunnyside was established in 1887. In 1887, a post office called Clyde Park was established at the historic Harvey and Tregloan Ranch, where John Harvey owned a Clydesdale horse which he had imported from England in the late 1890s. A stagecoach from Livingston, Montana, reached the town in the 1880s.
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 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.
