The South Dakota state doesn’t intrude that much into knife carrying and ownership.
There are no limits on any knife that can be owned. Open and conceal carry of any wife regardless of the blade length and knife construction
Since South Dakota State lack preemption laws, local ordinances can impose their knife laws. A knife owner should always be aware of the local legislation to avoid landing in trouble with the law.

Legal
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• It’s legal to own switchblades
• It’s legal to own gravity knives
• It’s legal to own balisong knives
• It’s legal to own butterfly knives
• It’s legal to own bowie knives, dirks, push knives, stilettos, hunting knives, daggers and KA-BAR knives
• It’s legal to own throwing stars, throwing knives and shuriken
• It’s legal to own sword canes, swords, bolo knives and machetes
• It’s legal to own undetectable knives and disguised knives
• Any legal knife can be carried concealed or openly
These knives can be possessed, made, bought, and sold legally.
Illegal
There isn’t any knife illegal to own or carry
Length Limit
There are no restrictions on the knife or blade length. However, some municipalities impose their local ordinances since South Dakota doesn’t have to preempt rule. For instance, Rapid City bans conceal carry of a knife whose blade length exceed 3”. Also, it’s illegal to carry a knife in any building selling liquor except folding knife whose blade length is below 3” and carried in a closed position.
Conceal Carry
South Dakota knife laws don't mention on conceal carry of knives and thus making it legal to carry all knives concealed.
Other Knife Laws in South Dakota
Considering that South Dakota doesn’t have preemption rule, a knife owner should always be aware of the local ordinances as they travel from different locations to another within the state.
Conclusion
It’s legal to own any knife in South Dakota irrespective on the knife construction and blade length. It’s also legal to carry any knife concealed or openly. But since some local ordinances impose their laws, a knife owner needs to be aware of the knife laws in every municipality in South Dakota State.
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