Help those white people remember. (The Washington Post) Help those white people remember. (The Washington Post)

Poli-Sci Perspective is a weekly Wonkblog feature in which Georgetown University’s Dan Hopkins and George Washington University’s Danny Hayes and John Sides offer an empirical perspective on the issues dominating Washington. For past posts in the series, head here.

When thousands massed on the Mall Saturday to celebrate the 1963 March on Washington, they weren’t simply marking the rally’s 50th anniversary. They were also helping sustain the significance of the civil rights movement in the public consciousness.

That’s the implication of a new article by researchers Amy Corning and Howard Schuman, who found that the 2011 commemoration of the 10th anniversary of September 11 increased the historical importance Americans ascribed to the terrorist attacks. Their findings also suggest that this weekend’s events may have their biggest effects on the attitudes of white Americans.

Large-scale anniversary celebrations can affect how the public thinks about historical events in large part because they draw so much media attention.

Corning and Schuman report that about two weeks before the 9/11 anniversary, the New York Times was publishing fewer than five stories per day that made reference to the terror attacks. In the days surrounding the anniversary, however, that spiked to about 35, an extraordinary amount of coverage that typically seems reserved for royal babies. (While the anniversary was obviously of particular interest to New York readers, the authors report that similar, if less dramatic, increases occurred on network television news and in USA Today.)

The uptick is important because a large social science literature has found that public concern over issues or events rises and falls as the media devote more or less attention to them.

Indeed, Corning and Schuman show that the same thing happened as Americans’ attention was refocused on the 9/11 attacks. Responses to a survey question that asked people to name one or two “especially important” national or world events that had occurred since 1930 appeared to be affected by the saturation news coverage.

In the weeks before the anniversary – but before the public commemorations began in earnest – about 25 percent of respondents mentioned 9/11 as an especially important historical event. Other common responses were World War II and the Vietnam War.

But during the peak of media coverage in the days around the anniversary itself, 40 percent of respondents mentioned 9/11. And even when coverage tailed off in the following weeks, the effect lingered, with 32% of respondents still saying 9/11 – higher than before the anniversary. The commemoration events appeared to have altered, at least temporarily, Americans’ assessments of the terrorist attacks’ historical importance.

Perhaps most interesting, Corning and Schuman find that the responses of black Americans were most strongly affected:

“We interpret this ... as indicating that the events an individual deems ‘deserving of remembrance’ may change depending on the identities a given context evokes. For blacks, the 9/11 anniversary commemorations may have affected the relative saliences of racial and national identities. Racial identity is usually salient for blacks but often ‘invisible’ for whites (McDermott and Samson 2005), and the events (other than 9/11) most frequently nominated as ‘especially important’ by blacks ... reflect that salience.”

The 9/11 commemorations then, may have raised the salience of national identity relatively more for blacks than for whites, leading to a larger increase in the share of African Americans calling the terror attacks an important event.

(Corning and Schuman also note that President Obama’s involvement in the 2011 anniversary may have increased the importance of the event for blacks, but their analysis does not allow them to distinguish between the two possibilities.)

These findings suggest that this weekend’s widely publicized commemoration of the March on Washington may have its strongest effects among white Americans.

The civil rights movement, Corning and Schuman report, is less chronically salient for whites than for blacks. As a result, media coverage reminding Americans of the struggle for civil rights may do more to increase the importance of the movement among whites than blacks, who already view it as a highly significant event.

Given the news of recent months – the acquittal of George Zimmerman in the Trayvon Martin shooting, the Supreme Court’s invalidation of part of the Voting Rights Act, and controversy over the New York City Police Department’s stop-and-frisk policy – the anniversary of the March may be the unusual event that helps bring the perspectives of whites and blacks closer together.