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 30 segment extended from US 77, west of White, to the Minnesota state line. Both segments were connected by 1960. Nearly the entire highway west of US 77, which is now I-29, was decommissioned by 1965. South Dakota Highway 30 South Dakota Highway 30 (SD 30) is a state highway in the east-central part of the U.S. state of South Dakota. It connects the north-central part of Brookings with the northeastern part of it. SD 30 was established in the mid-1950s. It had two segments, which were connected by the end of the decade. However, most of the highway west of