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.

South Dakota Highway 44 (SD 44) is a state highway in southern South Dakota that runs from U.S. Route 385 (US 385) west of Rapid City to Interstate 29 (I-29) south of Sioux Falls. It is just more than 379 miles (610 km) long.