[Christ]

Originally Posted by Quazar

1995 National Highway Designation Act returned all control of speed limits and enforcement to the state. This allowed states to determine maximum and minimum speed limits. If its posted, its illegal to drive above or below it.

Then why aren't loads of truckers and loaded/trailering pickups being fined on a daily basis?

You still haven't provided evidence of your claims that it is factually illegal to travel at a speed lower than the posted speed limit, while there is plenty of easily seen evidence suggesting the contrary.

Another example which suggests otherwise is that during inclement weather, it is recommended by (at least my local) DOT that drivers slow for road conditions to a safe speed, which assumes, based on your insights, that they're suggesting you break the law.