* The rise of the automobile: The development of the automobile in the early 20th century made it possible for people to live further away from their workplaces. This led to the expansion of cities into the surrounding countryside, as people sought out more affordable housing and larger lots.
* The growth of the middle class: The post-World War II economic boom led to a rapid expansion of the middle class. This group of people had more money to spend on housing, and they were also more likely to own cars. As a result, they were able to move to the suburbs, where they could afford larger homes and more land.
* The desire for a better quality of life: Many people move to the suburbs in search of a better quality of life. Suburbs are often seen as being safer, quieter, and more family-friendly than cities. They also tend to have better schools and more amenities, such as parks, shopping malls, and restaurants.
* Government policies: Government policies have also played a role in the growth of suburbs. In many countries, governments have encouraged the development of suburbs by providing subsidies for housing and infrastructure. They have also built new highways and other transportation networks that make it easier for people to commute to work from the suburbs.
As a result of these factors, suburbs have become increasingly popular in the developed world. They now account for a significant portion of the population in many countries, and they are continuing to grow rapidly.