The 30 Cleanest Cities in the World
Chicago, Illinois, USA
With over 2.7 million residents, Chicago is the third largest city in the USA but has a reputation of being a very clean and eco-friendly city. Chicago has planted over 186,000 sq m (2 million sq ft) of rooftop gardens throughout the city to improve the air quality, and it also encourages its residents to use public transport to reduce emissions.
