This may be the best way to measure gun violence in America - The Washington Post

There's an app for that

"The ShotSpotter system works by triangulating sound picked up by sensors placed on utility poles, light posts and buildings. The widespread use of what amounts to microphones in public has been criticized for privacy concerns. But supporters say the system is focused on reducing gun violence.

Nationwide, the number of gunfire incidents fell in 2015 compared to 2014, according to ShotSpotter data. The median reduction was nearly 13 percent in the 46 cities that used the system for comparable periods. These limitations makes it difficult for comparisons with other statistics, such as the Gun Violence Archive, which relies on media reports of shootings and found that the number of shooting incidents grew by 2.6 percent last year to 53,195."

This may be the best way to measure gun violence in America - The Washington Post