In 2022, the population of Spencer was 29, a 3.57% increase year-by-year from 2021. Previously, in 2021, Spencer's population was 28, a decline of 0.00% compared to a population of 28 in 2020.
The median age in Spencer, ID is 67.5, as per 2021 ACS 5-Year Estimates. Of the total population, 0.00% were under the age of 15, 4.17% aged 15 to 29, 25.00% aged 30 to 64, 70.83% aged 65 to 84, and 0.00% were 85 years of age and older.