As one of the megacities, New York experienced excessive growth and worsening environment in the 20th century. Since then, it has turned toward suburbanization.

Between the 1950s and 60s, residents gradually migrated out as policy stimulated residential development in suburbs.

Large shopping malls were built and industrial firms migrated to the suburbs. Satellite cities and towns catering for living, shopping and entertainment were built as New York saw a fundamental transformation in city structure.

Though suburbanization relieved urban pressure, it had side effects, including environmental pollution and too much expenditure on infrastructure.

Meanwhile, long distances between work and home added to time spent traveling and lowered people's quality of life.

In the 1990s, the city established a "prudent growth model": concentrating city building to narrow the distance between work and home as much as possible; redeveloping polluted industrial land and saving costs on infrastructure and public services. Currently, 85 percent of US cities subscribe to this model.