Filed Under The Environment

Dark Sky over Flagstaff

In 2001, Flagstaff, Arizona, became the first International Dark Sky City because of its long-term commitment to reducing outdoor light pollution without compromising safety. The Colorado Plateau’s clear, dry air, cloudless nights, and distance from major cities has made Flagstaff a significant location for astronomy.

Flagstaff’s history of dark sky conservation began even before the International Dark Sky City designation in 2001 when it issued the world’s first outdoor lighting ordinance in 1958. Lowell Observatory, founded in 1894 by Percival Lowell to study the surface of Mars, was concerned about how light pollution would limit the capacity of a reflecting telescope transferred from the Ohio Perkins Observatory. To protect astronomy, the Anti-Searchlight Law of 1958 passed to forbid the use of searchlights, common in advertising, within city limits.

However, light pollution levels kept rising in Flagstaff, even with the passing of a second lighting ordinance in 1972 requiring all outdoor lights be properly shielded and pointed downwards.  A shielded outdoor light has a surface or hood built in to prevent any light from escaping upwards or horizontally so the beam is directed at the ground. Fourteen years later, Tucson and Pima County updated their ordinances from 1973, and Lowell Observatory partnered with Flagstaff city planners to maintain Flagstaff’s status as an important site for astronomy.  In conjunction with the Arizona Public Service in 1987, Dr. Arthur Hoag from Lowell Observatory tested low-pressure sodium lights on Santa Fe Avenue in downtown Flagstaff as a method to reduce light pollution. With 90% approval from the public and evidence proving the new lights reduced the city’s light pollution, Flagstaff updated its lighting codes to mandate low-pressure sodium lights and ban mercury vapor light common in old streetlamps.  The amber hue of low-pressure sodium lights causes the least amount of sky glow, uses the least amount of energy to operate, and has the least impact on the natural rhythms of humans and nocturnal animals.  For astronomy, Christian Luginbuhl of the U.S. Naval Observatory documented that low-pressure sodium lights take up only two bands of the visible light spectrum, allowing astronomers to research within every other area of the light spectrum.

But in 1988, pressure from the Yellow Freight Company to allow higher levels of light pollution for a trucking yard near Lowell Observatory and the U.S. Naval Observatory Flagstaff Station split Flagstaff’s residents with arguments over economic and scientific interests.  The conflict ended in favor of continuing to reduce light pollution, and on September 26, 1989, the Flagstaff City Council enacted strict lighting codes for protecting Flagstaff’s unique natural. Yellow Freight withdrew from the city three years later.

The Daily Sun newspaper framed the clash over light pollution in Flagstaff as pitting money and jobs against scientific innovation and potential in the Daily Sun newspaper, but as time passed, the light ordinances did not harm Flagstaff’s economy.  In fact, the exceptional environmental conditions in Flagstaff grew the astronomical community with organizations such as the U.S. Naval Observatory and the U.S. Geological Survey contributing to a major tourism draw.  Residents and tourists alike interact with Flagstaff’s dark skies in different ways.  For example, the Flagstaff Star Party organizes every year with the help of astronomers Christian Luginbuhl and Jeff Hall from Lowell Observatory and helps residents and tourists learn how to observe the city’s dark skies  Another organization, the Flagstaff Dark Skies Coalition under Christian Luginbuhl, promotes music, art, and theater about Flagstaff’s skies in partnership with the Coconino Center for the Arts.

Flagstaff’s popular culture has grown to include the dark sky it is deeply proud of. In 2001, Flagstaff received an International Dark Sky City designation thanks to its conservation efforts and appreciation for a rare natural resource in the age of urban expansion.


Night sky in Flagstaff
Night sky in Flagstaff Source: “Milky Way over Flagstaff.” Deborah Lee Soltesz, July 14, 2020. Via Flickr (public domain). Creator: Deborah Lee Soltesz
First Dark Sky City
First Dark Sky City Dave Crawford (right), co-founder of the International Dark Skies Association, awarding the first ever Dark Sky City recognition in 2001 to Penny Trovillion (middle), Flagstaff city councilwoman, and Dave Wilcox (left), city manager. Source: Courtesy of the Flagstaff Dark Sky Coalition.
The difference darkness makes
The difference darkness makes Both photos depict the Summer Triangle; the left was taken in Flagstaff, AZ, and the right was taken in Phoenix, AZ. Juxtaposed, the images demonstrate the difference that dark sky preservation efforts make. Source: Courtesy of the Flagstaff Dark Sky Coalition, 2020.
Sodium streetlamps
Sodium streetlamps Light emitted by Low-pressure sodium streetlamps, like this one in Flagstaff, Arizona, takes up fewer bands on the visible light spectrum than other streetlamps do, such as mercury vapor lights. Source: Courtesy of the Flagstaff Dark Sky Coalition.


Flagstaff, AZ


Emma Svenson, Northern Arizona University, “Dark Sky over Flagstaff,” Intermountain Histories, accessed April 16, 2024,