More historic than 36% of U.S. towns · #103 of 285 in Washington. What drives it
Its Register listing is the Untitled Earthwork-Johnson Pit #30. Most of SeaTac was built recently: 5% of its homes predate 1940 and the median home dates from 1972. Below: maps from 1949 on and the census since 1980.
On its age, its old homes and the National Register, SeaTac is more historic than 36% of U.S. towns, #103 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 SeaTac’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 SeaTac’s 0.3 sits near the middle of its state (56% of Washington towns have fewer) while its 1 listings outnumber those of 51% 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 (±2.4 points) is firm at this size.
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 SeaTac’s past
Read from the archive, the National Register and the record. The page puts what stands out first.
Lost post offices, old corners and burying grounds
Another post office, Riverton Heights, opened and closed inside today’s town.
Hamlets and corners on the map
Angle Lake Mobile Home ParkBow Lake Residential Mobile Home CommunityDes Moines Estates Mobile Home ParkLatonaMcMicken HeightsMcVanRiverton HeightsThe Firs Mobile Home ParkTyee Valley Mobile Manor
2cemeteries and burying grounds inside SeaTac
Highview RecreationalWashington Memorial Park
US Post Offices dataset (Blevins & Helbock, CC0). Places and cemeteries from the USGS Geographic Names Information System (2021).
The earliest people to live in the Highline ridge and surrounding lowlands were Coast Salish peoples for thousands of years before European contact. The area sits between Puget Sound to the west and the Duwamish and Green River valleys to the east. It was used by Duwamish and Muckleshoot peoples for fishing, hunting, and overland travel. In the 1850s, federal surveyors recorded salal and huckleberry across the area, believed to be evidence of deliberate land management through intentional burning and cultivation, rather than pure wilderness. In 1990, a diver discovered two dugout canoes from the bottom of Angle Lake that were carbon-dated to approximately 1678. Both the Muckleshoot and Duwamish tribes claimed the artifacts, which were eventually transferred to the Muckleshoot Tribe for stewardship.
SeaTac is more historic than 36% of U.S. towns, #103 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 SeaTac?
One place: the Untitled Earthwork-Johnson Pit #30 (listed 2021).
How old are the homes in SeaTac?
5% of SeaTac’s homes were built before 1940 (Census estimate, ±2.4 points), against a typical 4.3% for a Washington town; the median home was built in 1972.
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), 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) 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.
2026
2011
