Why would you think that they were excluded from the census?
You think that was caused by “Jim Crow” laws? You are becoming a jerk.
Because legally they did not exist. Marriage between slaves was not recognized by law because slaves were not people. They were property.
You think that was caused by “Jim Crow” laws? You are becoming a jerk.
Even a jerk would know that "Jim Crow" laws were post rebellion, once your Black Codes had been cancelled.