What is the minimum turning radius of an SR-71? What is the minimum turning radius of an SR-71 at Mach 3.2 and an altitude of 80,000 feet? 

I have heard that if an SR-71 were to cross the Pacific coast over San Francisco and pull a hard turn to the right, it would return over Seattle. 

I'm interested in real-world performance, taking into account things like inlet unstart (failure to capture the engine inlet shockwave in the intake) from too sharp an angle of attack.
The Turn Radius of the SR-71 would depend on its speed. The faster it went  the wider its turn radius was. 

The SR-71 had a minimum turning radius at altitude of about 80 nautical miles (NM) . It was not an airframe limitation but a matter of wing area. At 80,000ft, the air is too thin and the wings too small to allow for much lift to turn with.

At a turn radius of 80 NM, the SR-71 would cover about 145 miles, taking about 4 minutes in the process of making a 180 degree turn. 

Details are provided in the SR-71 flight manual handbook, which is now declassified: