Very dark. Magnitude limit at my zenith (the area this photo was taken) was a little above 7th magnitude. I am fortunate that I live under this sky. It's right outside my door.
Jim
Ah...that explains it. I've taken digital images at faster effective exposures than the one you mentioned, and managed an all-white frame, so I was wondering how you did that on film. A dark site is obviously a big help in the whole sky-glow thing!