Since the 20th century, New York, a megalopolis, has gone through its own ongoing urbanization process, in which it evolved from a small city to a large one. However, the city's over expansion has worsened its residential environment. Correspondingly, the municipal government re-adjusted its city development strategy. It began to seek development in the suburbs.
From the 1950 s and the 1960s, the U.S. government encouraged high and middle income earners to buy houses in the suburbs on one hand. On the other hand, it kept improving the traffic network between satellite towns and city centers. Spurred by these incentives, New York residents gradually moved to the suburban areas. Subsequently, shopping malls were set up in suburban areas, to which industries and businesses were transferred. Finally, the city center came to a great relief. At the same time, satellite towns were equipped with housing, shopping and entertainment facilities. Accordingly, fundamental changes have taken place in New York.
Nevertheless, suburbanization has led to unbridled low-density city expansion. The society is subjected to severe environmental pollution and heavy cost of infrastructure investment. Meanwhile, commuting between residential sites and working sites has increased the cost of time, thus lowering urban residents' life quality.
In the 1990s, the United States embraced the concept of "smart growth". Urban construction tended to be relatively concentrated and clustered. Efforts were made to minimize the distance between living and working areas. Abandoned and polluted industrial land was re-developed to economize the cost of infrastructure and public services. At present, 85% of the United States' satellite towns are guided by this theory.