robert casey wrote:

Before the Interstates were built,
long distance driving was a real PITA.

So I've been told.

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).

Whole bunch of factors involved, like the Autobahns in Germany
and the success of toll roads like the Pennsylvania Turnpike.

Eisenhower was a big proponent of the interstate highway system.

There was also the concerted effort of the automakers, oil and
rubber companies, and even the concrete industry to get more
Americans to own and drive cars and trucks. They went so far
as to intentionally buy up and destroy transit systems (such
as the Pacific Electric in the Los Angeles area) so that
people would drive cars.

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.

Bombing bridges, particularly narrow ones like most RR spans,
is singularly difficult without special weapons. Highway bridges
are at least as vulnerable as RR bridges to such attacks.
73 de Jim, N2EY