This happened when I was a child of about 9 or 10 - so this would have been about 1961 or 1962.
I grew up in a housing development in Penn Hills, a suburb east of Pittsburgh, Pennsylvania, USA. Even as a child I loved the night - during Summer I used to walk around at night, enjoying the stillness and darkness.
One dark Summer night, about 4 A.M., I was walking up the driveway beside my house. Across the street was a house similar to my Cape Cod, also with a rear garage and a driveway that wrapped around the house. On the wall beside their driveway I saw four or five HUGE African- American men. They all looked alike - tall and very very muscular, with shaved heads. They were wearing the kind of overalls that buttoned over one shoulder, and no shirt. Although solid, they were an ashen gray color, clothes and all. When I saw them there was absolutely no sound - no birds or insects. The atmosphere was eerie - nothing seemed real. The men were milling about, some sitting on the wall and some standing. They seemed to move in a slow, jerky manner. One looked up at me. I saw that his face was very indistinct, with the features only suggested. I turned around and went back into the house. I will NEVER forget the apparitions. I can still see that scene vividly in my mind. I now know that what I saw were pre Civil-War Slaves slipping through the woods of rural Pennsylvania on their way to Canada. Never mind HOW I know this - I just do. I don't know if I slipped through time, or I saw their residual energy, or their ghosts, or what. I guess only a child could have been receptive to this...
This is true!!