Hello Hitch,
personally, i believe that Speed Limits of 80 to 90mph would be perfectly appropriate for almost all of the US Highways.

Any modern Car, and when i say Modern, i mean any Year 2000 and up Car, even the super small Smart ForTwo, can reach and maintain safely a speed of 90mph.

In Europe they have all super small cars, and they drive just perfectly at 150Kmh which is just about 90mph; i have drove over there at that speed with vehicles that in the US would be considered "tiny cars" and i felt perfectly safe because the Car was not shaking out of control, actually all the opposite: it was so smooth that i was having a normal conversation while driving at 90mph.

So, considering the US Highways are much less curvier than European Highways, i do not understand why in the United States of America, one of the most developed country of the World, there are still Speed Limits instated in the 80's... something really doesn't click.

And considering i am a frequent driver (for work i drive with my Car about 1000 miles a week) i wish i could travel a little bit faster so that i could get to clients earlier, but mainly, i can go back home earlier... PLUS, i often find myself having to go over the Speed Limit to keep myself awake because otherwise, driving at 65-70mph, i get distracted and i tend to fall asleep even during the day.

I think this is quite ridiculous, especially for a country where almost all of the circulating Vehicles are less than 10 years old.
Who ever has the power to review the Speed Limits, should do it after testing some of the modern Cars at these speeds
REGARDS