The NSA, CALEA, and the hardware backdoors built into routers (required by law)
http://www.dis.org/gessel/IS2K/CALEA_Carnivore.pdf
...but not everyone will, so here's an excerpt that relates to what I'm put in the title. The law the excerpt refers to is CALEA (Communications Assistance for Law Enforcement Act), which was passed in the 1990s:
"The law, as interpreted by the FBI, requires all companies providing telecommunications services in the United States to install remote control ports on their routers which allow law enforcement, acting autonomously and remotely (though theoretically only on a warrant) to easily extract any conversation in it’s entirety, up to 1% of the hub’s total traffic simultaneously. This capability must have been implemented by 1998, unless a waver until 10/24/2000 was granted. Given a large installed base of equipment, there was a controversial element of cost involved. The FBI played down the cost, asking congress to allocate $500 million. The FBI admits now that the cost may be 4-8 times that high. Industry estimates the cost at $10 Billion. Congress was convinced to allocate the original FBI estimate out of tax revenues, meaning the cost of implementation is borne by taxpayers. The difference in implementation cost is borne by customers of communication services."
Imagine how far things have come in the past 15 or so years.
To imagine that the US has anything less than the full capability to record and data-mine practically every electronically mediated communication is naive.