Seneca is a city in Grant County, Oregon, United States. It is located in the Blue Mountains about south of Canyon City, on U.S. Route 395, on the edge of the Malheur National Forest. As of the 2020 census, Seneca had a population of 165.
History
thumb|A church in Seneca
Seneca post office was established in 1895 and named by postmaster Minnie Southworth for her brother-in-law, prominent Portland judge Seneca Smith. At that time, large-scale shipping of Ponderosa Pine logs from Seneca and the surrounding national forest began to the Hines sawmill in Hines. Logging in the area began to decline in the 1970s, and the Hines company ceased operations of its lumber mills and railroad in 1984.
Situated at the confluence of Bear Creek and the Silvies River, Seneca is in Bear Valley at the northern edge of the Great Basin.
|source 2 = XMACIS2
Demographics
2020 census
As of the 2020 census, Seneca had a population of 165. The median age was 54.8 years. 13.9% of residents were under the age of 18 and 32.1% of residents were 65 years of age or older. For every 100 females there were 96.4 males, and for every 100 females age 18 and over there were 97.2 males age 18 and over.
There were 79 households in Seneca, of which 25.3% had children under the age of 18 living in them. Of all households, 45.6% were married-couple households, 16.5% were households with a male householder and no spouse or partner present, and 30.4% were households with a female householder and no spouse or partner present. About 27.8% of all households were made up of individuals and 20.3% had someone living alone who was 65 years of age or older.
! Race !! Number !! Percent
|-
| White || 153 || 92.7%
|-
| Black or African American || 0 || 0%
|-
| American Indian and Alaska Native || 0 || 0%
|-
| Asian || 0 || 0%
|-
| Native Hawaiian and Other Pacific Islander || 0 || 0%
|-
| Some other race || 1 || 0.6%
|-
| Two or more races || 11 || 6.7%
|-
| Hispanic or Latino (of any race) || 2 || 1.2%
|}
2010 census
As of the census of 2010, there were 199 people, 95 households, and 60 families residing in the city. The population density was . There were 128 housing units at an average density of . The racial makeup of the city was 99.0% White, 0.5% African American, and 0.5% from two or more races. Hispanic or Latino of any race were 1.0% of the population.
There were 95 households, of which 21.1% had children under the age of 18 living with them, 51.6% were married couples living together, 11.6% had a female householder with no husband present, and 36.8% were non-families. 31.6% of all households were made up of individuals, and 15.8% had someone living alone who was 65 years of age or older. The average household size was 2.09 and the average family size was 2.53. As of 2011, the school had 58 students.