Otoe County is a county in the U.S. state of Nebraska. As of the 2010 United States Census, the population was 15,740. Its county seat is Nebraska City. The county was formed in 1854, and was named tor the Otoe Indian tribe. In the Nebraska license plate system, Otoe County is represented by the prefix 11 (it had the 11th-largest number of vehicles registered in the county when the license plate system was established in 1922).