South Dakota Area Codes
Complete directory of all 1 active area codes serving South Dakota. The The Mount Rushmore State has a population of 919,318 (2023 estimate) and uses 1 area code.
About Area Codes in South Dakota
South Dakota (SD) is the The Mount Rushmore State, located in the Midwest region of the United States. With a 2023 population of 919,318 residents, South Dakota is served by 1 active area code. The state capital is Pierre and the largest city is Sioux Falls.South Dakota's official motto is "Under God, the People Rule."
Area code assignments in South Dakota follow the North American Numbering Plan (NANP), which has been in effect since 1947. As the state's population and demand for phone numbers grew — driven by the rise of cell phones, fax machines, pagers, and VoIP lines — regulators either split existing area codes geographically or added overlay codes that share the same territory. That's why South Dakota now has 1 codes: 605.
When you receive a call from a South Dakota number, the area code tells you only where the number was originally assigned. Because of Local Number Portability (LNP), which took effect in 2003, callers can keep their phone numbers even when moving across state lines. So while a 605 number was once assigned in South Dakota, the person calling you could be anywhere in the US today.
Time zones in South Dakota
South Dakota observes the Central and Mountain time zones. Daylight Saving Time is observed from the second Sunday in March through the first Sunday in November, when clocks shift forward by one hour. When you call a South Dakota number from outside the state, double-check the local time above each area code detail page to avoid calling at unreasonable hours.
Phone number format in South Dakota
All South Dakota phone numbers follow the standard 10-digit NANP format: (NPA) NXX-XXXX. For local calls within South Dakota, you typically need to dial the full 10-digit number — even for calls within the same area code — because of mandatory 10-digit dialing imposed by the FCC for areas with overlay codes (most of South Dakota's territory). For long-distance calls within the NANP, dial 1 + area code + 7-digit number.
Frequently asked questions about South Dakota area codes
How many area codes does South Dakota have?
South Dakota currently has 1 active area code: 605.
What is South Dakota's original area code?
The oldest area code(s) in South Dakota were assigned in 1947 as part of the original 86 NANP codes. These legacy codes typically covered the entire state at first, then were split as demand grew.
What time zone is South Dakota in?
South Dakota is in the Central, Mountain time zones.
Will South Dakota get more area codes?
As South Dakota's population and number demand grow, NANPA may assign additional overlay codes. When the current codes run out of available prefixes, regulators announce public hearings and propose new codes. The AreaCodeCentral team tracks these announcements and updates the directory within 24 hours of any new code activation.