These light pollution maps show several star parties. Oregon Star Party’s location is approximately 20 miles into the “black” (darkest) and may be the most pristine skies. GSSP and Texas Star Party are both on the gray/black border and probably share similarly dark skies.
Click maps for interpretation.
Mount Bachelor Star Party
Oregon Star Party
Texas Star Party
These light pollution maps are 173mi east to west, by 230mi north-to-south.