Something walking upright in Skamania County, Washington

My son (31) and myself were returning from a fishing expedition in the Gifford Pinchot Ntl Forest, SW Washington. All of a sudden, less than 100 yards away, we noticed an entirely black upright creature. Even though we're driving a noisy Cummins Diesel , when we came around the corner, going about 15 mph, we managed to startle it. It immediately walked fast - didn't run - from the right to the left, up a hill and was gone. Now this whole event didn't take more than 3-4 seconds. We immediately went to the area, and investigated. We found one print that was about 12-13 inches long on the side of the road. This print was made in the somewhat soft silt/gravel that is so common on forest service roads. It only was about 1/4-1/3 deep at best. Today we're going to try and make a copy of the print. A couple of things about the animal. 1. It was totally black, like a black bear. It had no facial features that we could detect at all. It didn't appear to have a nose, eyes, mouth or anything, that we could see from the 100 yards we were away. 2. The animal was in bright sunlight as it crossed the road - there was no mistaking it for a bear - and bears don't have 6 ft strides. 3. The animal appeared to be about 8-8.5 feet tall and slender build. It wasn't the massive muscular specimen I have thought they may be if they exist at all. I would estimate the weight in excess of 400 lbs. 4. The animal's arms moved in a pedulum manner, like an ape - not like a human. It moved very fast - BUT NOT a RUN!