Mass Surveillance in America: A Timeline of Loosening Laws and Practices

The long gap between 1978 and 2001 seems wrong. Off the top of my head it should mention the 1986 law that exempts email on public servers from the 4th amendment: https://en.wikipedia.org/wiki/Stored_Communications_Act

Forgot to add http://en.wikipedia.org/wiki/Carnivore_(software) and possibly http://en.wikipedia.org/wiki/ECHELON

This shows how it creeps. A change of policy here, a re-interpretation of the rules there, then over the years more and more is hoovered.

Be careful when they say things like "the program only looks at calls in which one end of the communication is overseas" (see Bush, 2006 in OP) ... because they distinguish between having the data, and looking at it (see https://news.ycombinator.com/item?id=5845258). Hence they claim that its OK for them to posses much more data than they should posses, as long as they only look at the bits they are allowed to look at. Dangerous.

An even more detailed timeline from EFF:

https://www.eff.org/nsa-spying/timeline

Missing from this timeline is the insidious shift of surveillance power from formal state security to far shadier private contractors.

The most damning fact to my mind is that, outside a very small circle, details of NSA spying are "too sensitive" to share with anyone in Congress. Meanwhile, nearly half of Booz Allen Hamilton's 25,000 employees have Top Secret clearances.