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 27,492 in 2024. 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).

Cass County was created on November 23, 1854, and was named for General Lewis Cass, an American military officer, politician, and statesman.

Cass County lies on the east side of Nebraska. Its east boundary line abuts the west boundary line of the state of Iowa, across the Missouri River.

According to the United States Census Bureau, the county has a total area of 565.891 square miles (1,465.65 km²), of which 556.911 square miles (1,442.39 km²) is land and 8.980 square miles (23.26 km²) (1.59%) is water. It is the 67th-largest county in Nebraska by total area.

Due to its proximity to Cass County, Iowa, and because both of those counties receive most of their broadcasts from Omaha, Nebraska, references to 'Cass County' must be frequently disambiguated, or result in confusion.^{[citation needed]}

As of the 2020 census, the county had a population of 26,598. The median age was 42.4 years. 23.9% of residents were under the age of 18 and 18.6% of residents were 65 years of age or older. For every 100 females there were 102.4 males, and for every 100 females age 18 and over there were 100.4 males age 18 and over.