Cass County was formed in 1854 and was named after the General Lewis Cass. Area Page: Eastern Lincoln Omaha Nebraska AreaCounty Seat: Plattsmouth NebraskaLicense Platte Prefix: 20Census 2010: 25,241Cities Towns in the County: Plattsmouth NebraskaCounty Map with Cities: Cass County MapWebsite - County: Cass County Nebraska Official WebsiteWebsite - County Fair: Cass County Nebraska County Fair
