Because there is rarely public transportation in the suburbs.
Lack of public transportation, mostly.
False
The automobile industry. In particular public transportation (the diesel engine).
A factor that did not contribute to the growth of suburbs is the decline in automobile ownership and usage. Suburbs typically grew due to factors such as increased automobile ownership, improved transportation infrastructure, and a desire for more space and privacy away from urban areas.
I think the first key to answering this question is understanding what the suburbs are. Most people consider themselves to either live in the city, or outside the city (the suburbs). The suburbs are usually less populated regions that do not contain the city life including lots of commercial buildings, big populations, and public transportation. In the city, most people could survive on public transportation. Nowadays, most cities have all sorts of transportation including buses, trains, subways, and taxi services. However, in the suburbs, there aren't as many public transportation. Hence living in the suburbs is pretty much a necessity to owning a car, unless you are comfortable walking, riding a bike, or any other means.
Certainly, as the personal vehicle became more attainable, and public transportation more abundant people were able to move away from the crowded cities and into the countryside.
Improvements in transportation
Cities are typically densely populated with a higher concentration of shops, restaurants, and cultural attractions, while suburbs are more spread out with a focus on residential areas. Cities tend to have better public transportation options, such as buses and subways, while suburbs rely more on private transportation like cars. Additionally, cities often have higher costs of living and more diverse populations compared to the suburbs.
One reason for the growth of suburbs was increased automobile ownership and improved transportation infrastructure.
Automobile
To help prevent pollution people could walk, ride bikes and use public transportation.