It is 1 of 12 Black History Months held throughout the year. It is held coincident with the 12 Hispanic History Months, German History Months, Eskimo History Months, et cetera.
In short, every month is simply an American History Month.
Morgan Freeman NAILS IT here:
Let's try not to be divisive (demagogues love it, I know).
E Pluribus Unum.