The story at the link is vague, the best I can make out these checkpoints are random and temporary kind of like a holiday weekend check points for drunk drivers, not sure if that is true but if they get 17 in one fell swoop imagine how many are getting through.
A spokeswoman for the U.S. Border Patrol says Friday that the mandatory checkpoint operated for five days on I-87 near North Hudson, 80 miles from the Canadian border. Motorists stopped at the checkpoint last weekend were asked to identify their citizenship.