Sunnyside dates to 1893, and 1 of its places is on the National Register
More historic than 34% of U.S. towns · #113 of 285 in Washington. What drives it
Most of Sunnyside was built recently: 5% of its homes predate 1940 and the median home dates from 1976. Its Register listing is the US Post Office-Sunnyside Main. Below: 6 old photos and papers, maps from 1908 on, and the census since 1910.
Founding year: Wikipedia. First post office: 1894.The full story ↓
History grade
What drives Sunnyside’s History grade
On its age, its old homes and the National Register, Sunnyside is more historic than 34% of U.S. towns, #113 of 285 in Washington. Its National Register listings hold the grade up; its share of homes from before 1940 pulls it down.
C
HistoryA character grade: shown, never part of Sunnyside’s overall grade.
Few Washington towns list much on the Register (a typical Washington town has 0.1 per 10,000 residents, the U.S. 2.4), so Sunnyside’s 0.6 sits near the middle of its state (58% of Washington 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 C− to C+. The pre-1940 share (±2.1 points) is firm at this size. Two sources give 1893.
Founding year: Wikipedia (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 Sunnyside’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.
Up through the early portion of the 19th century, the portion of the Yakima Valley where Sunnyside is now located was inhabited by the "Taptat-ħlama" (or ″People at the rapids"). These people hunted and fished along Yakima River from the mouth of Satus Creek (contained in present-day Satus immediately southwest of Sunnyside) to present Kiona, with a key fishery at near present-day Prosser.
Several tribes in the region were relocated onto the Yakama Indian Reservation following the 1855 signing of a treaty with the federal government. However, the Yakima War lingered until 1858, with Chief Kamiakin fighting on until the Battle of Four Lakes in 1858.
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.
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 1893, according to Wikipedia’s history of the town. Sunnyside’s post office opened in 1894, and the census of 1910 counted 1,379 people here.
How does Sunnyside rank for history?
Sunnyside is more historic than 34% of U.S. towns, #113 of 285 in Washington. 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 Sunnyside?
One place: the US Post Office-Sunnyside Main (listed 1991).
How old are the homes in Sunnyside?
5% of Sunnyside’s homes were built before 1940 (Census estimate, ±2.1 points), against a typical 4.3% for a Washington town; the median home was built in 1976.
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 (11), Wikidata (1), 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.
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