Time in South Dakota Time in South Dakota South Dakota lies in both the Mountain Time Zone and the Central Time Zone. Mountain Time roughly contains the western half of the state, but not all of it. Rapid City is the largest city in the Mountain Time portion of the state. Central Time contains the eastern half of the state and roughly more of the state than the Mountain Time Zone and includes the state capital Pierre and the largest city, Sioux Falls. The 2 zones for South Dakota as given by zone.tab of the IANA time zone database. Columns marked * are from
South Dakota Highway 36 in 1926. At that time, it continued further west to the Wyoming border, utilizing the current route of US 16A to Custer, and U.S. Route 16 west of Custer; US 16 went northwest from Rapid City. The western terminus was pulled back to its present location around 1935, when US 16 was rerouted southwest through the Black Hills. In 1933 and 1934, this route was also part of U.S. Route 216, which then continued north to Rapid City. South Dakota Highway 36 South Dakota Highway 36 (SD 36) is an east–west state route located in southwest South Dakota. It begins