Considering the fact that it is far and away the worst atrocity ever committed by American whites against other American whites, it had a remarkably low profile until quite recently.
I grew up in Missouri, where considerable time was spent in state history class discussing the Mormon War and other atrocities against the Mormons. The atrocity with the greatest number of victims had 13 or 17 males killed, I forget which.
As far as I remember, there was absolutely no mention of MMM, which realistically turns the Mormon/gentile conflict into one with a great deal of fault on both sides, not the unprovoked persecution of innocent sectarians that was presented in class.
I can absolutely guarantee that if a similar atrocity had been committed by American whites against blacks or Mexican-Americans it would have received a great deal more publicity over the years. MMM doesn't fit into the generally accepted narrative of American history.
Glad you forgot about the War of Northern Aggression.