The population of Curtiss City, Iowa, was 9,376 at the 2010 census. This was a fairly even spread. Twenty-five percent of residents were under the age of 18, and 7.9% were between the ages of 18 and 24. Twenty-four percent of residents were in the age group of 25 to 44. Only nine percent of the population was over the age of 65. The median age was 36 years old. The population of males outnumbered females by a ratio of 99.4 males for every hundred females, and a mere 4.9% of the population was 65 and older.