I believe that Interstate highways can realistically be driven at 90MPH

If that is the case, we need to re-educate drivers on the basics of highway driving again.

1. The left lane is the PASSING lane, not a travelling lane.
2. When merging from an on-ramp, match the speed of the traffic on the motorway
3. Do not pass on the left (related to 1)

I heard a comedy bit a while ago that went something like this: We should have a national system of driver rating. Everyone gets a high-powered suction dart gun, with darts that have little signs on them that say "Stupid Driver". If you see a stupid driver, shoot his/her trunk with the dart sign. If a cop notices 10 or so signs on the person's trunk, he'll pull them over, shoot them, and roll their body into the ditch.

I'm not so sure about the shooting part, but at least they could pull their license.