It must be February.
Now is the time when schools and libraries across the country stop doing real history and pretend to believe black people are important or interesting.
It's a coincidence that Black History Month1 is the month with Valentine's Day -- February was chosen because history teachers wanted to get it over with as quickly as possible2 -- but it's appropriate, because it's very much the same sort of thing: it's devoting a lot of attention all of a sudden to something which should be equally worthy of attention year-round. Just as saying "I love you" to your partner on all but 364 days of every year isn't the same as showing affection, saying "let's study the history of the black people now" for a month isn't the same as being inclusive. It makes February the back of the history bus.
(Right off the bat I make no claims to originality.)
1Googlefight found six times as many references to "black history" as to "African-American history."
2Fact not guaranteed accurate.