Answer:
Travel across the US became much faster
Drivers could reach other cities quickly.
To give you a little background, the 5th century was a time period where the roman empire had two kings. One to rule the west and the other to rule the east. This made it easier to oversee the entire land. (Rome was the biggest empire ever recorded.) By the end of the 5th century, though, western Rome had fallen to the hands of their enemies while the eastern part held their ground. Anyways, during the 6th century the overthrow of the roman monarchy took place, they vowed to never let another king rule over Rome again. Eventually a dictatorship resulted.
Migration led to the population of the world because human life started in Africa, meaning that for people to inhabit places that are now known as America, Europe, Australia, etc., they had to all migrate out of Africa.
The traffic increased as a result of the Louisiana Purchase
