Why is it illegal to drive at the posted speed limit of 70 MPH?

It isn't. But it is illegal to drive at 70 when the posted speed limit
is 55 (which it is for many places where 70 is perfectly safe). It's
also illegal to fly 210 feet above the ground while in clouds unless
you're on an instrument approach with an MDA of 210 or less. But that's
not my point.

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.