Platte is a city in Charles Mix County, South Dakota, United States. The population was 1,311 at the 2022 census. The community is named after the Platte Creek, a tributary of the Missouri River reservoir Lake Francis Case. Platte is located 15 miles east of Lake Francis Case on the Missouri River.

Charles Mix County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 9,373. Its county seat is Lake Andes. The county was created in 1862 and organized in 1879. It was named for Charles Eli Mix, an official of the Bureau of Indian Affairs influential in signing a peace treaty with the local Lakota Indian tribes. The easternmost approximately 60% of the county comprises the Yankton Indian Reservation.