In 1969 the federal government named Chattanooga the worst city in America for particulate air pollution — nylon stockings reportedly disintegrated outdoors. The city passed its air ordinance within months and reached full industrial compliance by 1972. Then in 1984 came the deeper turn: Vision 2000, a community visioning process where about 1,700 residents proposed and voted on 2,500 ideas, distilled to 40 public goals.
By 1992, Vision 2000 had produced 223 implemented programs and projects — the Tennessee Aquarium and riverfront revival most famously. Four decades on, the once-dirtiest city is North America's first National Park City, with a municipal fiber network and an outdoor economy. The trajectory change is traceable to a participatory process: residents at large, not a hand-picked committee, set the goals.
Mass participation isn't the celebration after a turnaround — in the best-documented American case, it was the ignition. A county that can ask its residents structured questions and publish honest counts owns the same ignition system Chattanooga used, at county scale, standing.
Chattanooga had foundation money (Lyndhurst) and a metro's scale; the mechanism transfers, the budget doesn't.
Sources: Vision 2000 — the process and its outcomes · Air Pollution Control Bureau — the 1969–72 cleanup history · Project for Public Spaces — the Riverpark transformation · National Geographic — America's first National Park City