Every combatant government attempted to minimize news about the 1918 flu for obvious reasons. It's called the Spanish flu because they were allowed to write about it.
It did kill more people than died in the war, perhaps 1/3 to half the world's population was infected and ten percent died (or those sick).
Imagine something that lethal with delayed onset of symptoms.
Don't.
Most paved roads followed whatever paths were already there obviously, some of which were literally cow paths.
Atlanta is hilly enough to have a nongrid base of roads outside near downtown. Driving in LA was nice because of the grid in the valley floor.