During the post-World War II period, landscape architecture's pre-eminence in urbanism was challenged by the new "scientific" profession of city planning. Riding the coattails of the growing popular faith in technology and progress, planners took control, relegating landscape architects to the sidelines. But during the '60s and '70s, the planners stumbled—badly. Their formulations turned out to be misguided and resulted in such debacles as urban freeways, public housing projects, and urban renewal. The planning profession never recovered from these failures and retreated to the bureaucratic thickets of zoning legislation, environmental impact studies, and community participation. That left an opening for landscape architects to take a leading role in shaping cities once more.