Ann Arbor, Mich., home to the main campus of the University of
Michigan, announced that it intends to become the first U.S. city to
convert all of its downtown streetlights to LEDs
(light-emitting diodes). The energy-saving lights use half the energy
and are expected to last five times as long. In two years, when the
city of 113,000 completes the conversion of all 1,046 streetlights,
they’ll cut CO2 emissions by about 2,425 tons a year. Ann Arbor has
already converted all its traffic lights to LEDs.

sources: 

The Ann Arbor News


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City of Ann Arbor press release [PDF]