Just three years ago, Detroit’s 139 square miles were lit only sporadically; around half of the 88,000 old streetlights were dysfunctional, their wiring decades old. In 2014 the city started a $185 million project to switch on 65,000 new LED street lights. The project was completed a month ago. The energy efficient LED lights now bring new life to neighborhoods and reduce Detroit’s carbon emissions by around 40,000 tons a year—equivalent to removing 11,000 cars from the streets.