The population of Atka is nearly entirely Aleut (Unangan). The major industry is fishing.
According to the U.S. Census Bureau, the city has a total area of 36.2 square miles (93.7 km²), of which, 8.7 square miles (22.6 km²) of it is land and 27.4 square miles (71.0 km²) of it (75.81%) is water.
There were 32 households out of which 40.6% had children under the age of 18 living with them, 37.5% were married couples living together, 9.4% had a female householder with no husband present, and 34.4% were non-families. 28.1% of all households were made up of individuals and 9.4% had someone living alone who was 65 years of age or older. The average household size was 2.69 and the average family size was 3.33.
In the city the population was spread out with 30.4% under the age of 18, 7.6% from 18 to 24, 29.3% from 25 to 44, 23.9% from 45 to 64, and 8.7% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 100.0 males. For every 100 females age 18 and over, there were 106.5 males.
The median income for a household in the city was $30,938, and the median income for a family was $34,375. Males had a median income of $28,750 versus $33,438 for females. The per capita income for the city was $17,080. There were no families and 7.5% of the population living below the poverty line, including no under eighteens and 26.7% of those over 64.
The Yakov E. Netsvetov School serves grades K-12.