My friend recently posted a picture on Facebook that he took while waiting to cross from Canada back into the United States. Here is his caption...

These little black squares at customs blink "top" in the top left in green then red then "right" in the bottom right in green and red. It does this repeatedly. Any guesses why?

And the object in question...

Nobody seems to know what these are. Someone speculated that the "TOP" is actually "STOP" and it was obscured or malfunctioning. Anyone have an explanation?

  • perhaps an indication on which the officer is sitting ? where is this by the way, I've crossed by car between US/Canada many times and I don't remember ever seeing this
    – blackbird
    Jul 25, 2014 at 17:02

1 Answer 1


The green / red is an indicator that it is your turn to approach the window to speak with the agent. When you approach the border you are supposed to stop outside the booth lane, then proceed to the window on green.

Not sure about the "right", as I have never seen that light before. I would guess that it means go to the right lane (by the small booth shown).

All the other equipment there is cameras, radioactivity detectors and other sensors.

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