You know, this apology stuff is really stupid.
As a white male, I apologize for slavery. I'm sorry slavery happened, and that people were hurt.
Okay, is that enough? Can everyone sit down and shut up?
The first census in Nebraska was in 1854, and there were 13 slaves in the whole state.
In 1860, the Nebraska territorial government abolished slavery, but it made hardly a ripple, what with just a few hundred people, mostly of mixed French-Indian derivation, in 77,000 square miles. It was a moot issue anyway, as even those 13 slaves from six years earlier were no longer around, or were no longer slaves.
(Native Americans were not counted in the censuses; there were probably 10-20,000 Sioux, Cheyenne, Omaha, Pawnee, Otoe, whatnot around at the time.)