In South Dakota, the maximum duration of a standard residential lease is one (1) year. Leases for more than one year are valid, but a written contract is necessary (SD Codified L § 43-32-5 (2019)).
Oral leases are acceptable for leases shorter than one year. Still, it is recommended that all lease agreements be in writing, as it is easier to enforce a written lease.
If there is no term defined by the lease, the tenancy is presumed to be for one year (SD Codified L § 43-32-3 (2019)).
The information for this answer was found on our South Dakota Residential Lease Agreement answers.