<P> Suburbs first emerged on a large scale in the 19th and 20th centuries as a result of improved rail and road transport , which led to an increase in commuting . In general , they have lower population densities than inner city neighborhoods within a metropolitan area , and most residents commute to central cities or other business districts ; however , there are many exceptions , including industrial suburbs , planned communities , and satellite cities . Suburbs tend to proliferate around cities that have an abundance of adjacent flat land . </P>
<P> Suburbs first emerged on a large scale in the 19th and 20th centuries as a result of improved rail and road transport , which led to an increase in commuting . In general , they have lower population densities than inner city neighborhoods within a metropolitan area , and most residents commute to central cities or other business districts ; however , there are many exceptions , including industrial suburbs , planned communities , and satellite cities . Suburbs tend to proliferate around cities that have an abundance of adjacent flat land . </P>
the growth of suburbs and urban sprawl were primarily facilitated by
the growth of suburbs and urban sprawl were primarily facilitated by
improved rail and road transport , which led to an increase in commuting
improved rail and road transport , which led to an increase in commuting