What Are The Small Blue Lights On Some Minnesota Stoplights?

Ever driven through an intersection in Minnesota and noticed a small blue or purple light near the traffic signals and wondered, "What is that?"

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The lights, often mistaken for cameras, are actually part of a clever system helping Minnesota law enforcement keep our roads safer, in a way you might not immediately think of.

As you floor it through a yellow-that’s-basically-red light, the cops are sitting in the distance, watching -- and they already know what you did. They’re not guessing; they’re staring at that sneaky little blue light, that just tattled on you.

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So, what exactly are the blue lights at intersections and how do they work?

These blue lights are part of Minnesota’s traffic signal system designed to help police officers catch red-light runners without needing to sit right at the intersection and without even having a view of the red light at all.

Sgt. Troy Christianson of the Minnesota State Patrol shared how they work in his latest Ask a Trooper series:

Signal Activation: When the traffic light turns red, the blue light comes on automatically.

Officer Visibility: The blue light is strategically placed so officers can see it from a distance.

Enforcement: If you enter the intersection while the blue light is on, police know you ran the red light and can safely pull you over down the road.

Without blue lights, catching red-light runners turns into a two-officer job; one to watch the light like a hawk and another to pull the offender over down the road. The blue lights simplify all this, cutting the job down to one set of eyes and making enforcement both safer and more streamlined.

“These lights make it easier for officers to enforce traffic laws and help keep our intersections safer,” said Sgt. Christianson. “It’s about improving safety for everyone on the road.”

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Don’t expect these blue lights to be front and center, they’re often tucked away in plain sight, on the side of a traffic light pole, or sometimes sitting right on top of the traffic lights themselves.

These little blue lights aren’t exactly new; they’ve been quietly popping up across Minnesota intersections since around 2009–2014. But you won't see them everywhere. They’re typically reserved for high-risk intersections where crashes are more common.