How a “location API” allows cops to figure out where we all are in real-time

Cyrus Farivar:

The digital privacy world was rocked late Thursday evening when The New York Times reported on Securus, a prison telecom company that has a service enabling law enforcement officers to locate most American cell phones within seconds. The company does this via a basic Web interface leveraging a location API—creating a way to effectively access a massive real-time database of cell-site records.
Securus’ location ability relies on other data brokers and location aggregators that obtain that information directly from mobile providers, usually for the purposes of providing some commercial service like an opt-in product discount triggered by being near a certain location. (“You’re near a Carl’s Jr.! Stop in now for a free order of fries with purchase!”)