Cass County, Nebraska
Cass County is a county in the U.S. state of Nebraska. As of the 2020 census, the population was 26,598. and was estimated to be 27,657 in 2025. The county seat and the largest city is Plattsmouth.
Cass County is included in the Omaha–Council Bluffs metropolitan area.
In the Nebraska license plate system, Cass County was represented by the prefix "20" (as it had the 20th-largest number of vehicles registered in the state when the license plate system was established in 1922).