If the USA didn't have *this*? You wouldn't see the population
   density map as I showed you about. Human engineering. Gigantic
   government project, providing work for soldiers who came back
   from war.[1]640px-Map_of_current_Interstates.svg

References

   Visible links
   1. http://icopiedyou.com/wp-content/uploads/2015/09/640px-Map_of_current_Interstates.svg_.png