Highways are incredibly useful ways of transporting goods across the United States. Though many are over sixty, or seventy years old, the infrastructure remains solid. With the proliferation of highways, we now have easier commerce between states. The effects of a zombie apocalypse would change these highways in profound ways that would make them nearly useless.
Near a Large CityEdit
Highways leading away from a large city will be absolute death traps. Most people will most likely want to escape the city, in their rush it is not hard to imagine that a collision could occur that can result in total deadlock. Zombies would not be far behind and once they catch up and start banging on stopped cars and opening them like cans of sardines, the people in front of the horde will undoubtedly abandon their cars and try to escape on foot. With the exodus of city dwellers, now on foot having abandoned their cars, the highways would be scenes of unimaginable chaos. These people would wander around, aimlessly, in what is essentially a herd. Some would splinter off, but many would stay in the same group. Periodically, people would die off and the zombie horde would always be following them. Though it is hard to speculate exactly what would happen to them, but it would leave the highways seriously dangerous.
In the CountryEdit
Highways in rural areas would obviously be less dangerous. If people were to make a mass evacuation, there is much less of a chance of a breakdown of traffic. What would be dangerous though, is the threat of bandits. People in the country have much better access to firearms and usually have better survival skills than a city dweller. Though not all people will turn to being bandits, the stress of a zombie apocalypse on such well equipped humans cannot be discounted.
Even now, people are doing what they can to raise awareness over the deteriorating state of our highways. Every year, the government spends millions on the maintenance and creation of our highway system. With the government either collapsed or in retreat, highways would likely be on the list of “things that can wait until dead bodies die like they are supposed to”.