Dakota County is a county in the U.S. state of Nebraska. As of the 2020 United States Census, the population was 21,582. Its county seat is Dakota City. Dakota County is part of the Sioux City, IA–NE–SD Metropolitan Statistical Area. In the Nebraska license plate system, Dakota County is represented by the prefix 70. In August 2009, the Dakota County Board of Commissioners reversed a decision to abandon this system for alphanumeric plates upon introduction of new license plates in 2011.