An aircraft that isn’t really in a class by itself; it was a reconnaissance platform like other reconnaissance platforms, yet it certainly was unlike anything before it or since (I assume, lacking the security clearance to know that). It’s also the fastest thing with wings that takes off and lands with a human crew aboard (that we know of, anyway…there are rumors…and the SR-72), setting its (official) absolute speed record July 1976 of 2193.13 mph (though there have been rumors that the Air Force unofficially clocked it at 2242.48 mph…and the A-12, the CIA’s version which preceded the SR-71 is supposed to have been even faster) . Depending on which source one reads, the Blackbird made it across the Atlantic in just under two hours (3,461.53 statute miles in 1 hour, 54 minutes, 56.4 seconds at an average speed of 1,806.95 mph) and from California to DC in just under over an hour (1 hour, 17 minutes, 53.69 seconds at an average speed of 2,124.51 mph).
Designed and built by Kelly Johnson’s team at the famed Skunk Works at Lockheed, its first test flight was in late 1966, (though its close cousin, the A-12 from which the SR-71 descended, had been flying since 1962). Thirty-two ’71s were built of which twenty-nine were SR-71As and two SR-71Bs (the only dual-control Blackbirds built and intended for training; one SR-71C was built from a crashed 71A to replace one of the 71Bs that crashed). In late 1989, early 1990, DC politics spelled out the retirement of the Blackbird, but Bosnia (not to mention the Middle East and North Korea) resulted in that decision being re-examined in light of the tactical situation (and not who was doing whom) and its service life was extended. Its last flight on the Air Force inventory was 1990. Typical of its performance history, the last flight of the last in-service Blackbird, tail number 972 flown by Lt. Col. Ed Yielding and his RSO (Reconnaissance Systems Operator) Lt. Col. Joe Vida, took place on March 6, 1990, with a cross-country dash from Beale AFB to Dulles International in DC and broke four speed-over-distance records. These records still stand.
During its twenty-five years of service, it’s rumored that over four thousand surface-to-air missiles were shot at it without a hit. No Blackbird was lost on a mission, twelve being lost in non-mission accidents, with one fatality.
The technology to build the Blackbird didn’t exist until Lockheed invented it. Its shape was intended to make the aircraft difficult to see with radar. Its published service ceiling (how high it can fly) is 85,000 feet and the top speed admitted to is Mach 3.2+. Because of the environment of the extreme altitudes it operated at, the crew’s flight suits looked like astronaut suits (no surprise considering they were based on the flight suits used by the Gemini program).
Upon its arrival at Dulles, #972 was turned over to the Smithsonian Air-Space Museum where it is presently displayed at the NASM’s facility in Virginia.

Tail number 61-7972 displayed at Steven F. Udvar-Hazy Center, Washington Dulles International Airport, Chantilly, Virginia