WASHINGTON — It was hailed as the dawn of a "post-racial America," ushered in by the election of the first black president in a country still scarred by the legacy of slavery, Jim Crow and the battle for civil rights.

But recent incidents -- including the shooting of an unarmed black teen by a white Hispanic neighborhood watch volunteer -- have revived concerns about America's racial divide.

Just a few short years after President Barack Obama's historic 2008 election, when many Americans believed the country had finally taken the upper hand over race, some are asking where the dream of a post-racial America went.

"I'm not so sure it ever existed," said law professor Athena Mutua of SUNY Buffalo Law School, whose work focuses on issues of race and the African American community.

Mutua said many Americans embraced the historical significance of Obama's White House win, creating the illusion of a colorblind society where racial issues were no longer a major concern.

"The whole country says, 'Wow, this is a euphoric moment. We've transcended our baggage,' and post-racialism was born with Obama's election," she told AFP.

"Of course, it wasn't real."

Mutua said reports at the time exaggerated the level of white backing for candidate Obama, giving the impression that the country had advanced further than it had.

"I think people painted that picture of wide support for Obama, but I think they overplay that. Obama did not get a majority of the whites in this country to vote for him. It was a high number, but certainly not a majority," she said.

And his election "stirred up all the unresolved issues in the country" among those reticent to racial change.

"His being there immediately galvanizes the opposite forces -- stuff that's really tinged with racism," Mutua added.

The Trayvon Martin shooting is the latest flashpoint where race, which periodically flares up as a contentious national talking point in America, again seized the national spotlight.

The 17-year-old was shot dead in February by George Zimmerman, who told police he found the youth suspicious while patrolling a gated community in Sanford, Florida.

Civil rights advocates and black Americans who decried the slaying as a possible hate crime said it was an indictment of a racially insensitive criminal justice system that appeared ready to let an alleged white perpetrator walk free because the victim was black.

Zimmerman has been charged with second-degree murder in the youth's death, but only after weeks of national protests during which he was in hiding and the appointment of a special prosecutor to handle the case.

But beyond the teen's shooting, many Americans have been stunned to see the coarseness of the racially tinged debate leading into November's reelection battle in which Democrat Obama will square off against presumptive Republican nominee Mitt Romney.

In one incident, a judge earlier this year was forced to apologize after sending his colleagues a racially derogatory joke about Obama on his office email.

Many Americans also were taken aback by an anti-Obama bumper sticker that used a racial slur, becoming a hot seller on the Internet by urging voters "Don't Re-Nig in 2012."

Critics have accused some conservatives of using coded and racially-charged language, pointing, for example to Newt Gingrich's description on the campaign trail of Obama as America's best "food stamp president."

"People call that 'dog whistling.' You know that that's a racist remark, and he's not fooling anybody with that," Mutua said.

Republicans, however, bristle when accused of a racial animus in their dislike of Obama, saying that their qualms with the president have to do with his politics, not his skin color.

For his part, Obama has declined to enter the fray, denying that his race plays a role in the public's perception of who he is, or the work he is doing.

Johns Hopkins University assistant professor Lester Spence saw real signs of progress in Americans' "acceptance of difference," including in pop culture -- even if he wouldn't term the changes "post-racial."

He cited the broad-based societal acceptance of African Americans as some of the country's most adored figures in music, media and popular culture, saying it had a role in bringing about broader shifts in attitudes.

"Racial attitudes are really complex," said Spence. "People love (hip hop artist) Jay-Z, they love Lil Wayne -- people consume blackness every day somehow on TV," he said.

There are also great strides in the political sphere.

"At the national level, black people are being treated as citizens in a very different way than they were even just 10 years ago before the election of Obama," Spence said.

But at the local level, where incidents like the Martin shooting are investigated and prosecuted, "it still hasn't trickled down that far yet," he added.