What is the population of Colbert City, Iowa? This small city in the state of Iowa is home to more than 24,000 residents. The population is primarily white, with a mix of Hispanic and Native American heritage. There are a number of schools and public libraries in Colbert City. The median age in the city is 43 years old. The median household size is 2.27 people. As a result, Colbert City is one of the most diverse cities in the nation.