In 2007 The Rockefeller Center tree christmas tree started using light-emitting diodes, or LEDs as their lighting system; The tree outside the United States Congress is lit the same way. These organizations are switching to LED lighting for a reason; It is clean and green. And LEDs lower the carbon footprint and make the tree more environmentally friendly. New York City wants to migrate the lighting of the Brooklyn Bridge to LEDs. LEDs last three times longer than normal lights. They last for 24,000 hours, before burning out. This is about 1,000 days. The lighting consists of 24-watt LEDs which are replacing 100-watt bulbs. While the current draw is much lower there will not be an appreciable drop in the brightness of the lights. The same light output with less current draw means a more efficient lighting system. This means a cleaner lighting system. The largest benefit is reduced greenhouse gas emissions. Electricity production in the United States is mostly from coal or natural-gas fired power plants; This reduction of electricity use dramatically alters the carbon footprint of the bridge reducing emissions of CO2 and smog-forming pollutants. The effect of changing the bridge from existing lighting to LEDs is equivalent to removing 400 cars from the streets!