Dark Sky Laws by State: US Outdoor Lighting Rules

Six states, Arizona, Arkansas, Delaware, Maine, Michigan, and New Mexico, have a genuine statewide outdoor lighting law on the books, according to the primary statutes collected here. Seventeen more states have limited laws that cover only state buildings, highways, or a single issue like sea turtle nesting, and the remaining 28 states plus Washington, D.C. have no statewide statute at all, leaving the job to cities and counties, as the National Conference of State Legislatures confirms. Below is the full 50-state-plus-D.C. table, a matching table for Canada's provinces and territories, and a plain explanation of what these laws actually require.

Why outdoor lighting got legislated

Outdoor lighting law grew out of four separate pressures that converged over the last four decades. The earliest driver was astronomy: observatories at Kitt Peak, Mount Lemmon, and Lowell Observatory pushed Flagstaff, Arizona to pass a searchlight ordinance in 1958, decades before any state acted, and that same pressure produced Arizona's 1986 statewide statute described below. Wildlife protection followed: Florida's Marine Turtle Protection Act and Illinois's Bird-Safe Buildings Act both restrict lighting specifically to stop disoriented hatchlings and migrating birds from flying into buildings. Energy and cost concerns show up in nearly every state-facility statute on this list, such as Maryland's and Minnesota's, which require efficient, shielded fixtures on public buildings to cut wasted light and wasted electricity together. Most recently, glare and light trespass, one neighbor's light spilling into another's yard or bedroom window, has driven a wave of municipal nuisance-lighting bylaws, including Calgary's Community Standards Bylaw and Mississauga's Nuisance Lighting By-law.

Safety is the counterweight in every one of these debates: nobody is arguing for unlit streets, only for light that is shielded and aimed down instead of spilled sideways and up. That distinction, glare versus usable light, is the core idea behind every ordinance on this page, and it is explained in more detail in our guide to dark-sky-friendly outdoor lighting.

Dark sky laws in all 50 states and Washington, D.C.

"Statewide law" below means a real outdoor-lighting or light-pollution statute applies broadly across the state. "Limited law" means the rule covers only state-funded buildings, highways, a single wildlife issue, or a voluntary program. "No statewide law" means regulation, if any, exists only at the city or county level. Click any state to see its full statute list, municipal codes, and sources on its own page in the dark sky laws hub.

The states that led the way

Five states anchor the story of how dark-sky law actually spread. Arizona passed the first statewide outdoor lighting law in 1986, building on Flagstaff's 1958 searchlight ordinance and the observatory-protection movement around Kitt Peak and Lowell Observatory; Flagstaff itself became the world's first International Dark Sky Place in 2001. Thirteen years later, New Mexico's Night Sky Protection Act of 1999 became the second statewide law, requiring shielded fixtures and putting an 11 p.m. curfew on lit sports fields except to finish a game in progress. For nearly two decades no other state followed with a comparably broad statute. Delaware adopted a narrower rule in its 2005-2006 legislative session, defining light pollution and requiring cutoff luminaires, but only for outdoor lighting fixtures built or replaced with state funds, not a general statewide framework. Maine closed that gap in 2026: its Act to Promote Responsible Outdoor Lighting takes effect October 1, 2026, capping new public lighting at 3000 Kelvin, requiring full shielding above 1,000 lumens, and giving municipalities until December 31, 2028 to extend similar rules to private property. Massachusetts may be next: its Dark Skies bill passed the Senate in 2026 and was still working through the House as of August 2026, without having reached the governor's desk.

Canadian provinces and territories

No Canadian province has a broad, dedicated outdoor-lighting statute comparable to Arizona's or New Mexico's. Instead, protection comes from a patchwork of municipal bylaws, provincial park policy, and federally managed national parks, several of which carry a Royal Astronomical Society of Canada (RASC) Dark-Sky Preserve designation.

Quebec's rules stand out as the most detailed in Canada: three regional municipalities around the Mont-Megantic International Dark Sky Reserve, Sherbrooke, Haut-Saint-Francois, and Granit, jointly cap upward light spill at 1 to 2.5 percent and set 10 p.m. or 11 p.m. curfews on non-essential outdoor lighting.

Municipal ordinances: where most of the real protection lives

Because 28 US states and most Canadian provinces have no statewide law, cities and counties do the actual regulating. Two Arizona examples show the range: Flagstaff's lighting code traces to a 1958 searchlight restriction, while the joint city-county Tucson/Pima County Outdoor Lighting Code, first adopted in the 1990s and revised in 2012 and 2024, limits shielding, total lumens, and color temperature to protect the observatories on Kitt Peak and Mount Lemmon. In Colorado, Westcliffe and Silver Cliff adopted a joint ordinance to become the state's first International Dark Sky Community in 2015. In Ontario, Huntsville's bylaw required full cutoff, downward-shielded fixtures on new construction starting in January 2016 and gave existing property owners until January 2026 to upgrade, while also restricting dock lights to warm amber or yellow tones. Florida takes a hybrid approach: the state maintains one statewide model lighting ordinance for sea turtle protection, and it only takes legal effect where a county or city, such as Volusia County or Sarasota, formally adopts it.

If your town has no ordinance at all, New Jersey's voluntary model lighting ordinance template and the joint IDA-IES Model Lighting Ordinance, the reference document most US municipal codes on this page draw from, are the two most useful starting drafts for a town council to adapt.

What a good outdoor lighting ordinance actually requires

Whether it is a 1986 state statute or a 2025 township bylaw, the ordinances that hold up over time converge on the same handful of rules, closely tracking DarkSky International's five principles for responsible outdoor lighting: light should have a clear purpose, be directed only where needed, be no brighter than necessary, be controlled with timers or motion sensors, and use warmer color temperatures. In statute language, that becomes four concrete requirements. Shielding: fixtures must be "fully shielded" or "full cutoff," meaning no light escapes above the horizontal plane of the fixture, the core requirement in Arizona's, New Mexico's, and Maine's laws. Color temperature: newer laws such as Maine's cap fixtures at 3000 Kelvin or lower, and Quebec's Mont-Megantic zone goes further at 2200K, because bluer, cooler light scatters more in the atmosphere and washes out more stars. Brightness limits: rules are typically written as a lumen threshold, commonly 1,800 lumens (roughly a 100-watt incandescent equivalent) in Maryland's and Minnesota's statutes, above which shielding becomes mandatory. Curfews: New Mexico requires recreational field lighting off by 11 p.m., Maine requires nonessential lighting off between 10 p.m. and sunrise, and Quebec's regional rule sets a similar 10 or 11 p.m. cutoff for non-essential fixtures.

Homeowners looking to meet these standards on their own property, whether or not their town requires it, can find fixture-by-fixture guidance in our dark-sky-friendly outdoor lighting guide.

How to push for a lighting ordinance in your town

Every ordinance on this page started with a resident or a small group raising the issue with a town council or county board, usually with three ingredients: a specific complaint (glare from a new development, a sports field kept lit past bedtime, or a stargazing spot losing its view), a model to point to (the IDA-IES Model Lighting Ordinance or a neighboring town's bylaw, such as Huntsville's), and a champion on the council willing to sponsor a vote, the path New Hampshire's law explicitly encourages towns to follow even without mandating it. DarkSky International's own International Dark Sky Places program certifies parks, communities, and preserves that adopt qualifying lighting rules, giving a town a concrete, marketable goal to organize around, similar to how Westcliffe and Silver Cliff, Colorado and Bon Accord, Alberta built their bylaws around that same certification. Once a rule passes, the certified parks and preserves it protects show up in our dark sky places directory, and the celestial events worth protecting a dark view for are tracked on our events calendar.