South dakota constitution
Article XVII: corporations
Section 14

No railroad corporation shall consolidate its stock, property or franchises with any other railroad corporation owning a parallel or competing line; and in no case shall any consolidation take place except upon public notice given out, at least sixty days to all stockholders, in such manner as may be provided by law. Any attempt to evade the provisions of this section, by any railroad corporation, by lease or otherwise, shall work a forfeiture of its charter.