Lost River is a city in Custer County, Idaho, United States. The population was 68 persons at the 2010 census. Geography Lost River is located at (43.721785, -113.544931). According to the United States Census Bureau, the city has a total area of , of which, is land and is water. Its name refers to its location near the Big Lost River. Demographics 2010 census As of the census of 2010, there were 68 people, 15 households, and 11 families residing in the city. The population density was . There were 30 housing units at an average density of . The racial makeup of the city was 95.6% White, 2.9% African American, and 1.5% from two or more races. Hispanic or Latino of any race were 11.8% of the population. There were 15 households, of which 33.3% had children under the age of 18 living with them, 73.3% were married couples living together, and 26.7% were non-families. 13.3% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older. The average household size was 4.53 and the average family size was 3.36. The median age in the city was 47.5 years. 11.8% of residents were under the age of 18; 7.4% were between the ages of 18 and 24; 23.5% were from 25 to 44; 47.1% were from 45 to 64, and 10.3% were 65 years of age or older. The gender makeup of the city was 63.2% male and 36.8% female. 2000 census As of the census of 2000, there were 26 people, 8 households, and 6 families residing in the city. The population density was 3.0 people per square mile (1.2/km2). There were 15 housing units at an average density of 1.7 per square mile (0.7/km2). The racial makeup of the city was 84.62% White, 11.54% from other races, and 3.85% from two or more races. Hispanic or Latino of any race were 30.77% of the population. There were 8 households, out of which 50.0% had children under the age of 18 living with them, 75.0% were married couples living together, and 25.0% were non-families. 12.5% of all households were made up of individuals, and none had someone living alone who was 65 years of age or older. The average household size was 3.25 and the average family size was 3.83. In the city, the population was spread