Declining populations and shuttered factories have left rustbelt cities - like Buffalo or Rochester - with numerous vacant and abandoned properties. They can be old homes, former warehouses, or out-of-favor shopping centers.
Municipalities face the challenge of how to get those properties back into productive use.
Kevin Caravati is an urban green space expert with the Georgia Tech Research Institute. He calls those empty sites "red fields" - a play on the term for environmentally contaminated sites known as "brownfields." He has worked in cities across the country, including Atlanta and Cleveland, to turn vacant properties into parks, gardens or nature sites.