CHICAGO (CBS) — A news release earlier this month intrigued the CBS 2 Morning Insiders – it announced that Lollapalooza foot traffic on State Street set a record.

The release said more than 2 million people walked down That Great Street during a recent seven-week period.

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But really – how in the world do they know that?

CBS 2’s Vince Gerasole found out, and took us inside the task of counting people on the move Friday morning.

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As you rush by on State Street, corner to corner and block by block, you’re being watched and counted every hour of every day. Sensors on high that you don’t even see are counting the number of pedestrians who pass the stores and restaurants below.

“We get it up this high so we can count everything including vehicles,” Michael Edwards, chief executive officer of the Chicago Loop Alliance, told Gerasole from the roof of the Palmer House Hilton.

On that roof, a pair of sensors provide images with software that zeros in on pedestrians, places yellow squares around those they track, and counts them. The sensors are even capable of discerning individuals from groups walking together.

Sensors are also set up to count simultaneously in multiple directions.

For three years now, the sensors are how the Chicago Loop Alliance has let its member merchants know pedestrian counts along State Street. The reach is just about 1.5 million pedestrians a week in the winter – a number that jumps to 2 million and beyond in the summer.

But the Palmer House Hilton rooftop isn’t alone. It is one of a number of locations up and down State Street where the sensors are mounted on high, taking count of the people passing below.

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“Chicago has one of the most complicated systems,” Edwards said. “So there’s 136 what they call countlines.”

It breaks down thusly – at nine different intersections, there are countlines on each sidewalk running north and south on both sides of the street, and countlines running east and west on each sidewalk on both sides of the cross-street.

In addition, there are countlines for the traffic flow in moving in each direction at every intersection.

“You’ve got to think of it as eyeballs on the street,” Edwards said. “Those are all opportunities to stop someone and have them eat in your restaurant.”

The pedestrian counts, available in hourly increments, help merchants decide everything from staffing to when to run sales. Springboard, the company providing the data, only shares the headcounts – not the video – with the Loop Alliance.

Edwards said there should not be a concern about Big Brother watching.

“Not really, because all I get is a number,” he said. “I can’t tell you who was on State Street. I can just tell you 2.2 million people were on State Street last week.”

So the next time you venture down That Great Street, know that you can count on being counted.

The sensors show State Street traffic has dropped about 2.5 percent in recent years. That is better than the national average for commercial areas, which has dropped 2.8 percent.

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The reason is that more people are shopping online.