Columbia City is a city in Columbia Township, Whitley County, Indiana, United States. The population was 8,750 at the 2010 census. The city is the county seat of Whitley County. There were 3,018 households out of which 30.6% had children under the age of 18 living with them, 45.8% were married couples living together, 12.4% had a female householder with no husband present, and 37.9% were non-families. 33.6% of all households were made up of individuals and 15.1% had someone living alone who was 65 years of age or older. The average household size was 2.27 and the average family size was 2.89.