Billions of cellphone locations are apparently collected daily by the NSA of the “whereabouts of cellphones around the world” according documents from NSA contractor Edward Snowden.  On December 4, 2013 the Washington Post reported:

The NSA does not target Americans’ location data by design, but the agency acquires a substantial amount of information on the whereabouts of domestic cellphones “incidentally,” a legal term that connotes a foreseeable but not deliberate result.

One senior collection manager, speaking on the condition of anonymity but with permission from the NSA, said “we are getting vast volumes” of location data from around the world by tapping into the cables that connect mobile networks globally and that serve U.S. cellphones as well as foreign ones. Additionally, data are often collected from the tens of millions of Americans who travel abroad with their cellphones every year.

Based on this report it will be interesting to see how the US government and its allies around the world react to apparent surveillance of private citizens.