The National Security Agency (NSA) is gathering nearly 5 billion records a day on mobile phone locations around the world. The NSA is also able to track activity it deems suspicious. The government is tracking people from afar into confidential business meetings or personal visits to private visits to medical facilities, hotel rooms, private homes and other traditionally protected spaces. Officials said the programs that collect and analyze location data are lawful and intended strictly to develop intelligence about foreign targets. The purpose of this program is to identify terrorists and their networks overseas.
Source: https://thehackernews.com/2013/12/co-traveler-nsas-cellphone-location.html