[minnesota_bound]

The plane was flying a mile every 1.6 seconds, well above our Mach 3.2 limit. It was the fastest we would ever fly.
http://sploid.gizmodo.com/5511236/the-thrill-of-flying-the-sr-71-blackbird

1.6 x 60 x 60 = 5,760mph

[PIF]

I have heard a number of people dispute/ridicule any thing above mach 3 for the SR-71 no matter what some article claims. 5760 mph (1.6sec/mile X 60seconds X 60minutes) is something like mach 7.5, which would have made the plane hypersonic.

7.5 is not simply above the 3.2 limit, but astronomically above it.

[Ozark Tom]

1 mile per 1.6 second equals .625 miles second.

1/1.6 x60x60 = 2,250 mph