Suburbanization can be linked to a number of different push and pull factors. Push factors include the congestion and population density of the cities, pollution caused by industry and high levels of traffic and a general perception of a lower quality of life in inner city areas. Pull factors include more open spaces and a perception of being closer to "nature", lower suburban house prices and property taxes in comparison to the city, and the increasing number of job opportunities in the suburban areas. Improvements in transportation infrastructure encourage suburbanization, as people become increasingly able to live in a suburb and commute into the nearby town or city to work. Developments in railways, bus routes and roads are the main improvements that make suburbanization more practical. The increase in the number and size of highways is a particularly significant part of this effect.
