YozoraAtlas

How dark is the sky in the United States?

Sky darkness for 1504 towns and parks in the United States, worked out from NASA satellite images of light at night (2025). 741 of them have skies of Bortle 4 or darker, where the Milky Way shows overhead. The darkest is Bering Land Bridge National Preserve (21.95, Bortle 2), the brightest Las Vegas (16.61, Bortle 8).

19 Bortle class, 1 pristine to 9 city center park or dark-sky place city

Numbers like 21.95 or 16.97 are the brightness of the sky overhead on a clear, moonless night, in mag/arcsec². The scale runs backwards: a lower number means a brighter sky, from about 22 for a natural sky to about 17 in a city center.
How the readings are made

NASA satellite night-lights map of the lower 48 US states with every place marked

Alaska

Hawaii

Darkest skies in the United States

Among the places on this site. Plenty of land between them is just as dark, with no town or park to name it by.

Brightest city skies in the United States

Darkest place in each state of the United States

State	Places	Dark places Bortle 1 to 4	Darkest place
Alabama	11 places	2 dark	Russell Cave National Monument20.62 · Bortle 4
Alaska	25 places	23 dark	Bering Land Bridge National Preserve21.95 · Bortle 2
Arizona	64 places	40 dark	Kaibab National Forest21.90 · Bortle 2
Arkansas	13 places	5 dark	Arkansas Post21.46 · Bortle 4
California	222 places	84 dark	Modoc National Forest21.89 · Bortle 3
Colorado	44 places	26 dark	Rio Grande National Forest21.86 · Bortle 3
Connecticut	17 places	4 dark	Orient Beach State Park20.71 · Bortle 4
Delaware	1 place	0 dark	Wilmington17.71 · Bortle 8
District of Columbia	1 place	0 dark	Washington17.12 · Bortle 8
Florida	87 places	26 dark	Dry Tortugas National Park21.92 · Bortle 2
Georgia	26 places	7 dark	Stephen C. Foster State Park21.43 · Bortle 4
Hawaii	13 places	12 dark	Koke'e State Park21.90 · Bortle 2
Idaho	27 places	21 dark	Nez Perce National Forest21.91 · Bortle 2
Illinois	36 places	11 dark	Shawnee National Forest21.10 · Bortle 4
Indiana	25 places	5 dark	Turkey Run State Park20.77 · Bortle 4
Iowa	14 places	4 dark	Effigy Mounds National Monument20.99 · Bortle 4
Kansas	10 places	3 dark	Mushroom Rock State Park21.49 · Bortle 4
Kentucky	14 places	6 dark	Land Between the Lakes National Recreation Area21.08 · Bortle 4
Louisiana	13 places	6 dark	Poverty Point21.45 · Bortle 4
Maine	9 places	8 dark	Baxter State Park21.88 · Bortle 3
Maryland	12 places	1 dark	Assateague Island National Seashore21.25 · Bortle 4
Massachusetts	22 places	7 dark	Savoy Mountain State Forest20.90 · Bortle 4
Michigan	45 places	20 dark	Pictured Rocks National Lakeshore21.87 · Bortle 3
Minnesota	53 places	38 dark	Judge C. R. Magney State Park21.88 · Bortle 3
Mississippi	6 places	3 dark	Emmett Till and Mamie Till-Mobley National Monument21.23 · Bortle 4
Missouri	25 places	11 dark	Grand Gulf State Park21.44 · Bortle 4
Montana	23 places	20 dark	Upper Missouri River Breaks National Monument21.92 · Bortle 2
Nebraska	13 places	8 dark	Samuel R. McKelvie National Forest21.91 · Bortle 2
Nevada	26 places	16 dark	Humboldt-Toiyabe National Forest21.92 · Bortle 2
New Hampshire	7 places	5 dark	Mount Washington State Park21.57 · Bortle 4
New Jersey	17 places	0 dark	Jackson19.07 · Bortle 6
New Mexico	40 places	34 dark	Gila National Forest21.91 · Bortle 2
New York	40 places	18 dark	Adirondack Park21.65 · Bortle 4
North Carolina	37 places	19 dark	Cape Hatteras National Seashore21.55 · Bortle 4
North Dakota	5 places	2 dark	Theodore Roosevelt National Park21.34 · Bortle 4
Ohio	17 places	2 dark	Wayne National Forest20.78 · Bortle 4
Oklahoma	16 places	5 dark	Alabaster Caverns State Park21.66 · Bortle 4
Oregon	58 places	48 dark	Fremont National Forest21.90 · Bortle 2
Pennsylvania	31 places	17 dark	Cherry Springs State Park21.57 · Bortle 4
Rhode Island	3 places	1 dark	Montauk Point State Park21.04 · Bortle 4
South Carolina	9 places	3 dark	Devils Fork State Park20.65 · Bortle 4
South Dakota	8 places	6 dark	Badlands National Park21.79 · Bortle 3
Tennessee	19 places	5 dark	Pickett Civilian Conservation Corps Memorial State Park21.20 · Bortle 4
Texas	93 places	23 dark	Big Bend National Park21.93 · Bortle 2
Utah	50 places	35 dark	Bears Ears National Monument21.91 · Bortle 2
Vermont	3 places	3 dark	Moosalamoo National Recreation Area21.50 · Bortle 4
Virginia	38 places	19 dark	George Washington National Forest21.31 · Bortle 4
Washington	64 places	41 dark	Chelan National Forest21.78 · Bortle 3
West Virginia	9 places	9 dark	Monongahela National Forest21.50 · Bortle 4
Wisconsin	28 places	16 dark	Apostle Islands National Lakeshore21.85 · Bortle 3
Wyoming	15 places	13 dark	Yellowstone National Park21.90 · Bortle 2