The Madville Times pointed me to this from the South Dakota Department of Public Safety, of which the Highway Patrol is a part.
Prevent primitive behavior by signing up for sobriety checkpoint alerts and safe ride reminders delivered to your mobile phone. You'll receive a text message when there's a sobriety checkpoint planned in your county.
Madville said this....
So this would be Big Brother helping me keep track of Big Brother. I'm having a hard time getting my mind fully around that one, and I'm sober!
It does seem a bit odd. I know that checkpoints are controversial; the Supreme Court upheld them for drunk driver detection but not for drug interdiction, and Clarence Thomas has commented that he wouldn't mind a chance to overturn the DUI precedent. Perhaps it's meant to provide some kind of legal cover. I may have to ask around.