I think there's a difference in highways; as in "intrastate" and
"interstate." I believe it's intrastate if it stays inside the boundary of
a state and "interstate" if it goes outside the boundary of a state.

Kim W5TIT



It's more to do with who funded the construction of
what highway. The Interstates were federally funded
(about 90%, 10% by the state that whatever interstate
highway is in). Before the Interstates were built,
long distance driving was a real PITA. That the
Dept of Defense partially funded the Interstates so
they would be able to get convoys of troops and stuff
to somewhere. Intersections with local roads were
designed so if a bridge was bombed, traffic could
still get thru (go on the off ramp and then across
the local road and back on on the on ramp).

Railroads worked well in WWII, but our mainland
for the most part wasn't bombed. Take out a railroad
bridge and things get bottled up for a while.