S.D. Codified Laws § 12-26-13
It is a Class 2 misdemeanor for any employer in paying his employees the salary or wages due them, to enclose their pay in "pay envelopes" upon which there is written or printed any political mottoes, devices, or arguments containing threats, express or implied, intended or calculated to influence the political opinions or actions of such employees.
It is a Class 2 misdemeanor for any employer, within ninety days of a general election, to put up or otherwise exhibit in his factory, mill, workshop, or other establishment or place where his employees may be working, any handbill or placard containing any threat, notice, or information that in case any particular tickets or candidate shall be elected, work in his place or establishment will cease in whole or in part, or that his establishment will be closed, or the wages of his workmen will be reduced, or other threats, express or implied, intended or calculated to influence the political opinion or the actions of his employees in voting.
Any corporation violating this section shall, upon proof thereof, forfeit its charter.
SDCL 12-26-13