Google Maps tracks all Android phones to build live traffic maps

…in March of last year, Google Maps became much more useful to drivers, because in addition to offering directions, they also started to offer real-time views of how congested the roads were. If a road is colored green, it means it’s moving along, but a yellow road suggests some traffic and a red road means even more congestion.

Google realized that as more and more people continued to switch to smartphones, they had a miniature army of traffic monitors that they could make use of. Thus, the traffic flow that you see on your map is a highly accurate real-time display of the number of Android phones that are currently trying to make that same trek.