Frontline

United States Of Secrets, Part Two

In the second part of "United States of Secrets," FRONTLINE explores the role of Silicon Valley in the National Security Agency's dragnet. As big technology companies encouraged users to share more and more information about their lives, they created a trove of data that could be useful not simply to advertisers, but also to the government. The revelations of NSA contractor Edward Snowden would push Silicon Valley into the center of a debate over privacy and government surveillance.