I think we need something similar to what @auschwitzmuseum are doing. So in the context of black history, A daily post of this day in Black history. So yes can cover events, such as the Tulsa Massacre, but could also cover the birthdays of important people but also events such as those involving the black women who worked at NASA and were fundamental to the space program (Amy Johnson et al).
I am from the Uk, and would find this useful, we don't celebrate MLK here like you do in the states so having the MLK day reminder was useful too.