Shrinking cities names the condition of urban areas that lose population and economic activity, leaving vacant housing, surplus infrastructure and abandoned land. The concept gained prominence through a major German research and exhibition project around 2004 and through studies of the former industrial belts of Europe, the United States and post-socialist eastern Europe. It prompted a rethinking of planning, which had long assumed growth, toward managing decline, demolition, greening and rightsizing. Detroit, Leipzig and many post-industrial towns became reference cases.
It forced planning to confront contraction rather than growth, generating new strategies for vacancy, demolition and the productive reuse of emptied land. Shrinking-city thinking reframed depopulation as a condition to be planned for rather than reversed at any cost.