A fourth model, introduced by Tony Garnier and further developed by Le Corbusier, Walter Gropius, and others in the first half of the twentieth century, looked at the city in terms of efficiency and function and tried to provide access to light, air, and space using new techniques of construction and transportation. In each of these models there was a strong belief that good city form contributed to the health and well-being of people, and that cities should be designed, yet each model hypothesized a different relation between people and spaces. In the United States urban design as a distinct profession within the environmental design fields did not appear until after World War II when the federal urban renewal and highway programs stimulated rebuilding of major portions of American cities. Today the field is being shaped in new ways by an increasingly pluralist society. The public realm is in the process of being redefined and reinvented.
Environmental change is more incremental and subject to increasing public review.
At the same time, many American cities are expanding at their edges at an unprecedented rate, while central cities are losing residents, jobs, and public support. A renewed focus on creative urban design is needed now more than ever.