Interesting tidbit on the
Interstate Highway System. Created by Eisenhower, it's specifications required a perfectly straight section one mile long
every five miles in order to land military cargo planes in case of national emergency. (if you pay attention when you're driving, you'll notice it).
Eisenhower noticed in WW2 that bombing just a few airstrips in a country could paralyze it's military and emergency response capability.
His idea was to populate the country with thousands of potential airstrips and make the country invulnerable.
It worked.
Interstates highways are all divided highways to accommodate the wingspan of aircraft originally, not for traffic safety.
And if you look close, you'll notice in the straight sections, the speed-limit signs are magically positioned a lot farther away from the side of road than all the other ones
.
On topic:
Like in a state emergency, (in a hurricane evacuation when they change all lanes to one direction) in the event of national emergency you can expect the government to take control of some critical sections of interstates.