Charles Montgomery:

In the third year of his term, Peñalosa challenged Bogotáns to participate in an experiment. As of dawn on 24 February 2000, cars were banned from streets for the day. It was the first day in four years that nobody was killed in traffic. Hospital admissions fell by almost a third. The toxic haze over the city thinned. People told pollsters that they were more optimistic about city life than they had been in years.

Old-ish, but a really interesting look into the tweaks that can alter a city’s happiness.