I heard somewhere that the nationwide 55 mph limit was set to control fuel usage for a period of time, and some noticed afterwards that mortality rates dropped.
Wikipedia's National Maximum Speed Law page says: "It was drafted in response to oil price spikes and supply disruptions during the
1973 oil crisis.
While Federal officials hoped
gasoline consumption would fall by 2.2%, actual savings were estimated at between 0.5% and 1%."
Turns out there are other factors that can play into reduced fatalities.
Where do you stop? If 55 mph is safer than 65 mph, might 45 mph not be safer than 55? That's my point; there's some often poorly-reasoned line people draw where one side's too dangerous, the other isn't. I'm curious how people draw that line where testing CO levels in scuba tanks is concerned.
It's a tangent outside the intended scope of this thread, & I doubt there are hard & fast answers to be had anyway, so probably better to accept various viewpoints have been expressed and let it go (or make a separate thread).
Richard.