Barack Obama's inaugural address was the first in a long time to resound powerfully enough to be worthy of marble. However, it was the first in the 220-year history of the custom in another way: its seasoning of black cadence. This was even more exhilarating in that the cadence played an integral part in the power of the oration.
Black English is a matter not just of slang, but of sentence structure and sound (why you can tell most black people's race over the phone, which is proven in studies). Some blacks use all three; Obama is one of the many who wields mostly the sound. Listen to the way he often ends sentences on a higher pitch than, say, Tom Brokaw would, with that preacherly hang-in-the-air. Or the way he often pronounces "history" as "historih," "ability" as "abilitih." His rendition of the word responsibility was indicative: with a cadence typical of Black English, capped by a final "ih." No President has ever intoned sentences in this way, because they were not black.
Contrary to the fabulistic notion that gets around here and there that Black English is an African grammar with English words, the sentence structure is basically a blend of regional British dialects that slaves heard from their masters and the indentured servants you learned about in grade school. The sound, however, is partly a legacy of the African languages the slaves spoke. Especially, the melodic quality of Black English, heightened in sermons and speeches, is a legacy of the fact that in many African languages, pitch is as important in conveying what words mean as accent. In the way he said responsibility, he was using language in a way that is warp and woof of the grammar of, for example, his father's native language Luo.
Black English has always been a fundamental aspect of the American landscape, and not just in the sense of its just being there "diversely." Southern white speech owes the heart of its sound and structure to whites back in the day speaking like their slaves. That is, it's no accident that Southern English is spoken exactly where slavery was most widespread.
However, over the past two decades, Black English has made its way even more deeply into the American mentality: It has become an unofficial lingua franca for young Americans of all colors. It is not uncommon to hear a group of teenagers speaking in Black English, and find when they pass by that they are actually Latino, Asian, or with the cohort under about 25, white. To Americans older than this, the affectionate response to Black English is more a matter of reception than active command. However, the mainstreaming of soul music starting in the late sixties, followed by the mainstreaming of hiphop in the nineties, today means there are a vast number of whites for whom Black English signifies warmth, truth, "reality."
It is certainly part of why Obama was elected. Imagine John Kerry or even either Clinton trying to get elected intoning "Yes, we can!" What made that seem prophetic, or even plausible, from Obama was that it was couched in a Black English intonation - partly church, maybe even a dash of street (a cousin of mine likes that Obama "has a bit of the ghetto in him"). This aspect of Obama's oratory got to as many whites as blacks. "He's just ..., he's just, oh, he's just ...!" white Obama fans would often exclaim as the Obamenon set in, grasping at the mot juste. Many of them had basically been to their first black church service. He was just ... well, black.
And yet what makes Obama's linguistic repertory especially resonant as an American phenomenon is that he speaks Black English as a second language. Growing up with a white mother, he did not acquire it on her knee, nor does one come away from Hawaii and Indonesia steeped in the cadences of Jay-Z. Black English is, for Obama, part of the identity he constructed as a young adult. In line with how seamlessly constructed that identity is, he's a great mimic. Not all black people who adopt Black English in their late teens or afterward pull it off as well as Obama; they tend to discharge it with an "accent," so to speak, that a native speaker can detect.
This is surely part of why Obama can speak with no hint of Black English's sound when he wants to. I first heard his voice when I tuned into his famous 2004 Democratic Convention address on the radio and didn't know it was him yet, and at first thought I was listening to a white speaker. If the only way he could speak was in some degree of black cadence, he would not have been elected. In being so deftly bidialectal, Obama can speak to all of America in a way that neither a John Edwards nor a Jesse Jackson ever could. What's interesting is that his black style--wielded sparingly, to be sure--is useful in reaching quite a few whites.
So: The son of an African immigrant picks up a sonority of speaking from the descendants of slaves brought here from Africa centuries before--and then uses it to help seduce a nation full of descendants of slaveholders into making him their master. Linguistically as in so many ways, Obama embodies the extent to which we are all more "fellow citizens"--as he opened his oration--than we might think.