Hotspots indicate areas in New York we project could be bright in the future due to changes in energy. Base data acquired from NASA's International Space Station aerial photography archives.

Hotspots indicate areas in New York we project could be bright in the future due to changes in energy. Base data acquired from NASA's International Space Station aerial photography archives.




The New York City Department of Transportation operates the most extensive lighting system in the United States with over 250,000 lights in its five boroughs. For the past half century, they have relied on high pressure sodium (HPS) and metal halide (MH) lights for this system, producing an amber blanket of light above the city that never sleeps. 

There are three components of a typical municipal streetlight: the base, the pole, and the luminaire, which contains a fixture and its light source. Near the end of Mayor Michael Bloomberg’s administration in 2013, city officials approved a $76 million project to retrofit all traditional municipal luminaires with energy-efficient light-emitting diodes (LEDs). According to the New York Department of Transportation, the conversion project is expected to save the city approximately $6 million in energy and $8 million in maintenance every year; this is despite the fact that there is a higher upfront cost for the LED luminaire technology. Full municipal conversion is planned by the end of 2017.

The introduction of LEDs as a municipal light source represents a major shift in illumination technology. The digital chips last up to three to four times longer than traditional light sources (15-20 years instead of 2-5), produce two to three times more light per watt, and spread illumination more evenly. LEDs also contain more blue wavelengths than high pressure sodium and metal halide luminaires. This means that LEDs emit a brighter and whiter light with higher color temperature ratings, measured in degrees Kelvin. 

On the streets of New York City, this bright future is already being felt by residents. Novelist Lionel Shriver, a resident of South Brooklyn where the luminaire conversion is already underway, describes the NYDOT plan as “mass civic vandalism.” Others describe the harsh lighting as akin to “a strip mall in outer space” or “a prison yard” — cold, unflattering, too bright.  

New York LED fieldwork, observing brightness levels.

New York LED fieldwork, observing brightness levels.


In 2016, a team of researchers from the National Oceanic and Atmospheric Administration and the Light Pollution Science and Technology Institute created a model of global light pollution called the “Atlas of Artificial Night Sky Brightness”. They stitched more than 300 regional maps together and analyzed altitude, the angle that urban light hits the atmosphere, and the reflection of that light back to the Earth’s surface. Their study revealed that light pollution has increased about 6% each year over the past half century and now, more than 99% of Americans experience light-polluted night skies. Their study also predicted an increase in worldwide light pollution if LEDs continue to be adopted globally, due to blue wavelengths being more easily scattered by the earth’s atmosphere and more easily perceived by the human eye.

Another potential implication of this city-wide retrofit project could mean improved pedestrian security and reduced criminal offenses such as burglaries and vandalism, although recent academic research on this topic provides mixed conclusions. 

Lastly, the LED conversion program could result in negative health outcomes. In a new report by the American Medical Association, researchers reveal that there is a link between LEDs and a decrease in melatonin production, which can disturb sleep patterns and increase the risk of cancer, diabetes, and heart disease.

Community groups and international dark-sky proponents are pushing for LED alternatives that reduce light pollution while being energy and cost efficient. If enough momentum and support builds for this initiative, the future night sky of New York could be dark.  

LED technology is also rapidly advancing. New luminaires are available with lower Kelvin ratings, and a lower number of blue wavelengths. They produce a warmer, softer glow, similar to traditional light sources, while maintaining the same energy efficiency levels as previous LED models. Future technological advancements might mean a decrease in brightness for New York.