Per capita personal income in the county â which ranked at the top in the metro area and third in Kansas â was $53,353, down 4.8 percent. Jackson County was next in the Kansas City area, with total personal income of $26.15 billion, down 0.43 percent. It ranks second in Missouri behind St. Louis County. Platte County, TPI $3.83 billion, up 0.28 percent (ninth); per capita personal income $42,266, down 1.25 percent (third). â¢ Cass County, TPI $3.39 billion, up 0.58 percent (11th); per capita personal income $33,840, down 0.32 percent (23rd).