Suburbs have of course always existed, but the proportion of the population living in them has grown significantly since the period you note. Between 1950 and 2

Suburbs have of course always existed, but the proportion of the population living in them has grown significantly since the period you note. Between 1950 and 2010, the suburban population quadrupled while the city center population doubled: http://energyfuse.org/wp-content/uploads/2018/01/suburb2.gif http://energyfuse.org/wp-content/uploads/2018/01/suburb2.gif