I think I saw an all black blue jay in my yard. It was acting like a young bird and was with a normal jay. Same size as jay so not a cowbird. In flight tail shaped like jay's not grackle's. It was in view for only about 10 seconds and I did not have bins so I cannot be certain.
My yard is next to Mt. Pleasant Cemetery and the jays move around a lot. Try the western half of the cemetery, along the south wall, east of the mausoleum.
