If we're having a MPH dick-measuring contest here, I do believe Texas beats them all (for now).
HWY130, also known as Pickle Parkway which goes between Round Rock and Seguin is mostly 85 mph.
Which because it's a limited-access tollway, means there are few, if any, cops on the road and people are usually going 95-100 mph.
If you like driving fast on smooth, well-kept pavement, this is the stretch