Seattle

I didn't know about intersections, but knew that some retail stores and businesses actually do this. Devices around the stores will listen for Bluetooth transmissions or even WiFi signals from phones to see where people are congregating, how long they're in the store, and all kinds of things. It's why Android and Apple changed to use random addresses for phones.

You and your devices give off a lot of unexpected signals that can be monitored and tracked. Some things could be good like monitoring dwell time at a business or even queueing time at Disneyland, others could be used for marketing at a company. Just something to consider the next time you use WiFi at a business.