South Dakota is served by a single area code as of 2026. This guide walks through which code it is, when it was assigned, how it has held up against population growth, and what the prospects look like for additional codes in the future.
The Short Answer
South Dakota currently has one active area code in service. The code has held its territory without needing relief since it was assigned, which reflects South Dakota’s population size and the rate at which new phone lines are being activated in the state.
By population, South Dakota ranks #46 nationally with roughly 924,669 residents as of the most recent estimates. That puts the state’s area code count in line with its population peers — denser, faster-growing states need more codes; smaller states need fewer.
The South Dakota Area Code
The active area codes serving South Dakota are listed below, in numerical order. Where a code is an overlay or a split-off from an earlier code, that relationship is noted.
- 605 — Entire state of South Dakota (Sioux Falls, Rapid City, Aberdeen, Pierre)
How South Dakota’s Area Codes Grew Over Time
South Dakota received its first area code, 605, when the North American Numbering Plan launched in 1947. That single code initially covered the entire state, and subsequent splits and overlays narrowed it over the decades that followed.
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Browse South Dakota Area Codes →- 1947 — 605 assigned as South Dakota's sole area code at the launch of the North American Numbering Plan, covering the entire state. It has never been split or overlaid.
- 2021 — 605 transitioned to mandatory 10-digit dialing by October 24, 2021, after 988 was designated nationwide as the Suicide and Crisis Lifeline, removing 988 as a usable local prefix.
What’s Next for South Dakota Area Codes
605 covers all of South Dakota and is not currently in jeopardy. NANPA’s most recent NPA exhaust analysis (April 2025) projects the 605 numbering plan area will not exhaust until around 2035, and no relief planning is underway. An earlier 2023 projection had flagged a possible need for relief as soon as late 2026, but the more recent forecast pushed that horizon out by roughly a decade, so a split or overlay for South Dakota remains a distant prospect.
Frequently Asked Questions
How many area codes does South Dakota have?
South Dakota has one area code, 605, which covers the entire state. It is one of a small group of states still served by a single area code, alongside places like North Dakota, Montana, and Wyoming.
What is the oldest area code in South Dakota?
605 is the oldest active area code in South Dakota, assigned in 1947 when the North American Numbering Plan launched. It remains in service today, though its geographic footprint has typically been reduced by subsequent splits and overlays.
What is the newest area code in South Dakota?
The most recent area code addition to South Dakota was 605, activated in 2021. New phone lines provisioned in its service area are increasingly drawn from this code as older overlays approach exhaustion.
What area code is Sioux Falls?
Sioux Falls uses 605, the same area code as the rest of South Dakota. Rapid City, Aberdeen, Pierre, Brookings, and Watertown all share 605 as well.
Why does South Dakota still have only one area code?
South Dakota’s population is small and spread across a large rural area, so demand for phone numbers has stayed low enough that 605 has never needed to be split or supplemented with an overlay. It has served the whole state since 1947.
Do I have to dial the area code in South Dakota?
Yes. Since October 2021, all of South Dakota requires 10-digit dialing for local calls. The change was made nationwide so that 988 could be reserved as the Suicide and Crisis Lifeline number.
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