The American interstate system is a wonder of the modern world.
As much as it allowed goods to be more easily imported, it allowed American goods to be more easily exported. (The US exports far more manufactured goods to Canada than it imports. American manufacturing is doing as well as ever and only keeps increasing.)
These days it's wonderful for fuel efficiency; trucks don't have to keep stopping for red lights and traffic is a small town every 20 feet. I've driven across Wisconsin / northern Michigan. On a NON-interstate highway, it really IS a small town every 20 feet. It takes forever to get anywhere. Northern Ontario may be full of 200-mile stretches of nothing, but you never have to slow down.
But it's also important for national security, allowing major evacuations for hurricanes and other natural disasters. Regular highways wouldn't cope - not just because of the number of lanes, but by going through a small town every 20 feet.
High school friends who grew up in the Soviet Union told me about how during harvest, university students and soldiers would be tasked to help out in the fields. And then there would be mountains of rotting grain, because they lacked the transportation to get it to market. Now, keep in mind that any non-nuclear war would be an endurance race. Like WWII Germany, resources and food could run out before weapons...
Soviet bombers criss-crossed America all through the cold war. Under NORAD, Canadian fighter jets would shadow them to the American border and join up again when they came back. They didn't always come back; perhaps flying on to Cuba. (This practice lives on via the
Treaty on Open Skies.)
America was OK with this, though it's not wise to tell Americans about it. A reconnaissance bomber would show Russia things the US WANTED them to see: "Look, we REALLY DO have scores of missile silos pointed at you! We'll open some silo doors so you can see the missiles!" And look at the vast, endless farms... all with tractors and combines and other equipment! And the endless rail network and
INTERSTATE HIGHWAY SYSTEM! Bomb any highway or rail hub, and we'll STILL have no problem getting food and other resources to market!
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