2020 census As of the
2020 census, Seneca had a population of 2,353. The median age was 37.9 years. 25.2% of residents were under the age of 18 and 14.6% of residents were 65 years of age or older. For every 100 females there were 104.6 males, and for every 100 females age 18 and over there were 101.3 males age 18 and over. 0.0% of residents lived in urban areas, while 100.0% lived in rural areas. There were 864 households in Seneca, of which 33.2% had children under the age of 18 living in them. Of all households, 54.1% were married-couple households, 18.1% were households with a male householder and no spouse or partner present, and 20.6% were households with a female householder and no spouse or partner present. About 21.4% of all households were made up of individuals and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.85 and the average family size was 2.67. The population density was . There were 939 housing units at an average density of . Of the housing units, 8.0% were vacant. The homeowner vacancy rate was 2.8% and the rental vacancy rate was 9.8%.
Income and poverty The median income for a household in the village was $74,907, and the median income for a family was $87,813. Males had a median income of $62,895 versus $24,083 for females. The
per capita income for the village was $34,832. About 13.1% of families and 15.2% of the population were below the
poverty line, including 23.7% of those under age 18 and none of those age 65 or over. ==Economy==