I-80 approximately 20 miles east of Grand Island
Large signs shortly before the checkpoint announcing "Drug Checkpoint Ahead" and "Drug Dog in Use Ahead." The actual checkpoint is not on 1-80 itself, but at the exit right after the signs. The officers probably expect that anyone carrying drugs will quickly try to exit to avoid a checkpoint, so the checkpoint is located at the exit, out of sight of the highway.
Of course I wasn’t carrying any drugs, so I wasn’t worried about proceeding on I-80, but when no checkpoint appeared, I realized it had to be at the only exit shortly after the signs. I wonder what the locals out in the remote Nebraska countryside think about getting stopped by the state troopers all day and searched for drugs when they take the only ramp from the highway to town.