Harrisonville, Missouri is the county seat of Cass County, Missouri and has a population of 10,019. Harrisonville is served by the Harrisonville R-IX School District. HarrisonvilleSmithville is located along the Little Platte River in Clay and Platte Counties, Missouri. It’s population of 8,425 residents is served by the Smithville School District, which has earned “Distinction in Performance for High Achievement” the highest level of accreditation available to districts in Missouri. Smithville Lake is a popular destination for boaters, fishing, water skiers and inner tubers and attracts about 1.5 million visitors per year.