They don't go anywhere, they are no longer in use by the Air Force.
What a goofy answer...
An SR 71 Blackbird can travel over Mach 3 (3 times the speed of sound). Mach speed varies a bit by air density but it is roughly 742mph. This means that at Mach 3 the Blackbird is traveling at about 2225mph. This is literally faster than some bullet speeds (30.06 for example), and is faster than the earth's rotation (you could leave New York and fly to Hawaii and get there earlier than you left New York).
3.5
About 3 times the speed of sound. (3 mach)
2200 mph
Black
The SR-71 Blackbird is 2,193 miles per hour fast or Mach 3, three times faster than the speed of sound.
Stratosphere
2193 mph
the stratosphere!
The SR-71 Blackbird was introduced into service in 1966.
It is the Lockheed SR-71 "Blackbird", a reconnaissance aircraft.
The maximum speed of a SR71 is 2,200 mph at 80,000 ft.
SR71 Blackbird Model M-21: maximum speed: 2211miles/h Generally, the given answer for all models of the SR71 is: "In excess of Mach 3", or more than three times the speed of sound. see related links below for more info