Streetlights everywhere are going digital, cleaning up the night skies, saving billions in wasted energy–and offering major windfalls for those who embrace the gold rush. Los Angeles, New York, Chicago, Shanghai, Copenhagen and scores of other cities around the world are deploying LEDs in an attempt to solve most, if not all, of the problems created by inefficient traditional lamps. Of the 140 million streetlights installed worldwide last year, only 19 million were LEDs, according to IHS Technology. By 2020 LEDs are expected to account for 100 million of the installed base of 155 million streetlights. Annual sales of LED streetlights will jump from $4.3 billion to $10.2 billion in the same time period. New York’s $76 million project will be the largest in the country: replacing 250,000 lights by 2017.