Here is an excellent documentary on the NSA by Front Line. There is a ton of great videos on YouTube as well, but this will get you started on educating yourself on how the surveillance of the public has evolved. Bill Binney, the ex Technical Director of the NSA preceded Edward Snowden’s appearance by many years.
https://www.pbs.org/wgbh/pages/frontline/government-elections-politics/united-states-of-secrets/the-frontline-interview-william-binney/
This is an incredible video as part of a huge series that appeared on PBS.