Hart's Pass and Meadow Campgrounds
Location:
The high North Cascades. Roughly 5 hours from Tacoma. Follow logging road north from Hwy. 20 at Mazama, about 13 mi. west of Winthrop. Use your discretion: the drive has been described as a "white-knuckle" experience and "the most-terrifying road in Washington." But, from what I've heard first-hand, it isn't that bad.
Description:
The place should provide close to the darkest skies possible in Washington State. There are two campgrounds. Meadows Campground sports an "astronomy pad", a 10 X 20’ concrete pad oriented north-south. This area was hit by a forest fire in 2003. The campground was rebuilt in 2004 and the skies should be quite open. (Description from a post at the MVAS.)
Directions and more information can be found at the U.S. Forest Service: http://www.fs.fed.us/wildflowers/regions/pacificnorthwest/HartsPass/index.shtml
Also see the discussion at the Maple Valley Astronomical Society Forum.
Light Pollution Map:
