The first known inhabitants of the Tualatin Valley were the Atfalati tribe, a subset of the Kalapuya ethnic group. Contact with Europeans in the late 1700s led to the spread of smallpox and other diseases, which devastated the Atfalati population. In 1851, due to population pressures from white settlers, surviving members of the tribe negotiated a treaty with the Oregon Territory ceding their ancestral lands throughout the Tualatin Valley to guarantee a small reservation on the banks of nearby Wapato Lake. This treaty was never ratified, and in the late 1850s, the U.S. government relocated the tribe to the Grand Ronde Reservation.
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 Wikimedia Commons (3), Wikipedia, U.S. Geological Survey historical maps, U.S. Census counts (via 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.