Ta-Nehisi Coates wrote a phenomenal piece in The Atlantic's Civil War commemorative issue, and he laments that so few blacks are students of the Civil War, noting that it was "their" war.
And for black people, there is this—the burden of taking ownership of the Civil War as Our War. During my trips to battlefields, the near-total absence of African American visitors has been striking. Confronted with the realization that the Civil War is the genesis of modern America, in general, and of modern black America, in particular, we cannot just implore the Park Service and the custodians of history to do more outreach—we have to become custodians ourselves.
I've noticed this too -- as both a Civil War historian and a student of the development of post-Reconstruction racism. But it doesn't surprise me considering the continued dominance of the Lost Cause mythology and how, for more than a century, the Civil War was the centerpiece for white resentment of black people.
Coates observed how Gettysburg, in particular, is attempting to erase the mythology by rightfully putting slavery front-and-center in its visitor center presentations (the slavery film is both stirring and completely accurate). The other oddity about Gettysburg is the prevalence of middle-aged men -- mostly right-wing -- walking around in Confederate garb and sporting Dixie flags. I don't imagine it's entirely appetizing for a black family to venture into O'Rorke's on Steinwehr and observe an entire company of rebel reenactors eating burgers and drinking beer, talking about how their ancestors could have won the battle and ultimately the war (thus preserving slavery) by redeploying south of the Union lines. Incidentally, Newt Gingrich wrote a book in which he fantasizes about such a maneuver.
That said, one of the most moving several minutes I ever spent at Gettysburg was during a Gettysburg Address "Remembrance Day" event when I observed thousands of reenactors -- blue and gray alike -- cheering the 54th Massachusetts African-American reenactor unit as it marched by in formation. I'll never forget that.
Read the Coates piece. You'll be glad you did.