Originally Posted by
Dudemon
Most US speed limits outside of cities and metro areas are 65 or 70 mph with a few at 75. These seem to be rates that most feel comfortable driving at and will minimize speed variance.
To be more precise, in the western half of the US there are great swaths of 75 mph (120 km/h) speed limits, and Texas has raised the limit on large stretches of I-10 and I-20 in west Texas to 80 mph (130 km/h).
Even with speed variance, on these open roads you often have a half-mile or more to note that you're overtaking a car or truck and move to the passing lane.