Seneca is a city in Grant County, Oregon, home to about 109 people across 0.8 square miles. Its ZIP code is 97873.
Homes sold for a median of $65 per square foot in the three months ending August 2026, a buyer’s market.
Each card is that ZIP code’s whole market, including any part outside Seneca. Seller’s market: under 4 months of supply; buyer’s market: over 6. Methodology
We’re writing up Seneca’s story and what everyday life there is like, for people thinking about moving in.
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| Nearest major airport | Boise Air Terminal/Gowen Field (BOI)142 miles away |
|---|---|
| Closer regional airport | Eastern Oregon Regional Airport at Pendleton (PDT)108 miles away |
| Nearest city of 250,000+ | Portland, OR204 miles away |
| Nearest city of 1 million+ | Los Angeles, CA699 miles away |
Straight-line distances from the center of Seneca; driving is longer.
Source: Airports from OurAirports (scheduled passenger service); city centers and populations from the U.S. Census Bureau.
Source: Members of Congress from the congress-legislators project; districts from the Census Bureau’s relationship files; governor and mayor from Wikidata.
Seneca had 165 residents in the 2020 census, down 26% since 2000.
It’s the 394th largest of 420 towns in Oregon by population.
Grant County grew from 5,948 residents in 1900 to 7,233 in 2020.
Grant County, 1900–2020
Source: U.S. Census Bureau decennial censuses (counties 1900–1990 from the Bureau’s historical county file).
Average highs peak around 82°F in summer, and winter lows average 11°F. About 13.6 inches of rain and melted snow fall in a typical year.
Source: NOAA 1991–2020 climate normals, Seneca, OR weather station (about a mile away).
1,543 jobs at 207 businesses in Grant County. The biggest industries by employees:
Source: U.S. Census Bureau County Business Patterns 2023 (private employers; jobs counted where people work).
Nearest hospitals
Source: Hospitals from CMS Hospital General Information (ratings are CMS overall star ratings); straight-line distances.
Public schools here are run by John Day SD 3. Check each district’s attendance zones for a specific address.
| School | Grades | Students | Type | Distance |
|---|---|---|---|---|
| Seneca Elementary SchoolSeneca | K–6 | 12 | Public | 0.1 mi |
Source: U.S. Department of Education, NCES: Common Core of Data (2024-2025) for public schools. Listed by address; we don’t rate schools.
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Town boundaries don’t always match ZIP codes: a ZIP code can cross into neighboring towns, and a town can share a ZIP code with its neighbors. Facts describe the town itself; market figures describe whole ZIP codes.