Barack Obama's success, as Congressman John Lewis put it recently, is another step on the long road toward laying down the "burden of race." But the growing use of the phrase "post-racial America" should worry us all.

Consider the results of one major social science study, published in Du Bois Review: Social Science Research on Race, which yielded some troubling results about segregation of neighborhoods in America. Researchers at the University of Illinois, Chicago and the University of Michigan surveyed a large representative sample of households in Chicago and Detroit. As part of this highly innovative study, every participant was handed a laptop and was asked to view a series of video clips showing different neighborhoods. The set of neighborhoods remained constant. But the video was altered to manipulate their make up, to show either whites populating the neighborhood, or blacks or a mixed-race population.

According to UIC Professor of Sociology Maria Krysan, what the study sought to determine was "whether whites are colorblind in their evaluations of neighborhoods or whether racial composition still matters—even when holding constant the quality of the neighborhood." The results clearly show that whites rated the neighborhood much more favorably when whites dominated the make-up. And the more negative the stereotypes a white individual held of African Americans generally, the more likely they were to negatively rate the identical neighborhood with a visible black presence.

This research combines new, high-quality data with grounded, real world problems and real world research techniques. While we would all like to believe that cues on social class now drive Americans more than those on race, it simply isn't true. As sociologist Krysan explained: "These findings demonstrate that 'objective' characteristics such as housing [quality] are not sufficient for whites to overcome the stereotypes they have about communities with African-American residents." Sadly, it was the race cues that mattered, not the class cues.

The study found much more ambiguous or "mixed" results for blacks. Blacks did judge schools to be of higher quality in mixed-race and all-white neighborhoods. But blacks were not so ready to judge black neighborhoods as negatively affecting the value of homes or the safety of a community. The results for blacks were thus not as strongly correlated to stereotypes as for whites. An earlier generation of research done in the mid-1990s did show that negative racial stereotypes held by blacks about whites (as well as toward Hispanics and Asians) play a part in judgments about desirable neighborhoods.

This study, many others before it and, no doubt, more to come in the future, signal the depth of both a structural and cultural problem of race in America. It is easy in the moment of joy surrounding a great triumph to overstate the amount of change that has occurred and the future pace at which change will continue.

Few scholars remark on it now, but it is worth noting that on May 17, 1954 Thurgood Marshall stood triumphant on the U.S. Supreme Court steps, after a unanimous Brown v. Board of Education decision. He boldly predicted to the assembled reporters that within five years, there would be no segregated schools in America. Well, as we all learned over the ensuing decades, one great victory in the battle against racial injustice does not bring the struggle to a definitive conclusion.

Barack Obama's election is an unparalleled achievement that we will all be celebrating for some time to come. His election shows, unequivocally, that we have done much to narrow the racial divide in America. At the same time, we must acknowledge that we have not dismantled a society still segregated by race in most of its neighborhoods and schools. And we have not erased the great economic disparities separating average black and white Americans. Seeds of mistrust and miscommunication along the color line are deeply sown and will continue to sprout ugly weeds.

The post-racial narrative is premature. One of the great challenges of the Obama era will be how to celebrate its promise, without taking our eyes off the prize.

Lawrence Bobo is the W.E.B. Du Bois Professor of Sociology and of African and African-American studies at Harvard University.