Dayville is a city in Grant County, Oregon, United States. It was incorporated in 1913. The population was 138 at the 2000 census. As of the census of 2000, there were 138 people, 59 households, and 36 families residing in the city. The population density was 269.5 people per square mile (104.5/km²). There were 77 housing units at an average density of 150.4 per square mile (58.3/km²). The racial makeup of the city was 96.38% White, 2.17% Native American, 0.72% Asian, and 0.72% from two or more races.