Hartline is a town in Grant County, Washington, United States.

According to the United States Census Bureau, the town has a total area of 0.33 square miles (0.85 km2), all of it land.

There were 87 housing units at an average density of 263.6 per square mile (101.8/km2).

33.9% of all households were made up of individuals, and 4.8% had someone living alone who was 65 years of age or older.

There were 77 housing units at an average density of 233.6 per square mile (90.1/km2).

36.7% of all households were made up of individuals, and 21.7% had someone living alone who was 65 years of age or older.

There were 5.7% of families and 8.5% of the population living below the poverty line, including no under eighteens and none of those over 64.