Plankinton is a city in Aurora County, South Dakota, United States. It is the county seat of Aurora County. Plankinton was named for Milwaukee meatpacker and hotel owner John Plankinton, a friend of Alexander Mitchell, the President of the Milwaukee Road. Plankinton was home to an annual wheat palace, which became a successful regional attraction and inspired the Corn Palace in nearby Mitchell, South Dakota. According to the United States Census Bureau, the city has a total area of 0.6 square miles (1.6km2), all of it land.