Area Code 605

About Area Code 605

Area code 605 is a geographic telephone area code assigned to Sioux Falls, South Dakota. It operates in the Central time zone and was first introduced in 1947. Original NANP code. State-wide South Dakota.

Within South Dakota, area code 605 is the only active area code, covering the entire state. The state's 919,318-person population (2023 Census Bureau estimate) is served by a combined 1 active code, with 605 primarily responsible for the Sioux Falls region. South Dakota's state capital is Pierre, and its largest city is Sioux Falls.

When you receive a call from a 605 number on your Caller ID, the call originated from a phone number assigned to the 605 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 605 only confirms where the number was originally assigned.

Where is the 605 area code located?

Area code 605 is assigned to Sioux Falls, South Dakota, in the Central time zone. The state of South Dakota uses 1 active area code, and 605 is the only one. Calls placed from the 605 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 605 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Central time zone observes Daylight Saving Time, shifting from UTC-6 to UTC-5 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 605 area code?

The 605 area code serves 15 notable cities, listed below in order of population. The largest city in the 605 territory is Sioux Falls (183,733 residents in Minnehaha County).

• Sioux Falls, SD — 183,733 residents (40.3% of 605 numbers)
• Rapid City, SD — 75,443 residents (16.5% of 605 numbers)
• Pierre, SD — 14,015 residents (3.1% of 605 numbers)
• Brookings, SD — 23,677 residents (5.2% of 605 numbers)
• Watertown, SD — 22,673 residents (5% of 605 numbers)
• Mitchell, SD — 15,738 residents (3.5% of 605 numbers)
• Yankton, SD — 14,767 residents (3.2% of 605 numbers)
• Vermillion, SD — 11,846 residents (2.6% of 605 numbers)
• Aberdeen, SD — 28,324 residents (6.2% of 605 numbers)
• Huron, SD — 14,265 residents (3.1% of 605 numbers)

Phone number format in area code 605

All phone numbers within area code 605 follow the standard North American 10-digit format:(605) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 605 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 605 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 605

Original NANP code. State-wide South Dakota.

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 605 area code safe to answer?

Area code 605 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 605 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.