I drove from Vegas to Disneyland a year ago. There was an agriculture checkpoint going from Vegas to LA. It was manned, but the guy waved us through. We were in a Chevy Malibu or some similar sedan with 2 (white) people. From Disneyland back to Vegas there was no check point.
It should be far enough away from a border that there cannot be a CBP checkpoint because I thought the supreme court ruling stated that immigration checkpoints had to be within 100 miles of a border. Unless they are counting the sea, they would just be harassing people for no reason.