Saturday's Promise Keeper march may be the largest gathering of its kind. But will its message reach the public?
It seems clear the Promise Keeper organization is on the verge of pulling off one of the single largest religious gatherings in American history.
What is unclear is if it will have any larger resonance beyond the experiences of those who participate.
The site of this weekend's march, the Mall in Washington, has been the venue for some of the nation's most visible protests dating back before the turn of the century.
But experts say their ability to impact America, and make the history books, is based less on their size than on the receptivity of the public to the message the groups are trying to convey. Marches that seem to sum up the nation's feelings or desire for social change are usually the most successful.
"Sometimes you think of these marches, and they reshape American history," says Harry Rubenstein, a political historian at the Smithsonian Institution. "They fall into a historical context. They are capstones that serve to solidify and acknowledge public opinion."
One of the earliest and most successful rallies, for instance, was the 1913 suffrage protest. Some 10,000 women marched down Constitution Avenue in hopes of winning their gender the right to vote. Troops were called in to quell violence caused by well-wishers - mainly men - still in town for Woodrow Wilson's inauguration. Despite the harshness of the day, the women garnered increasing public support for their cause.
More recently, the 1963 March on Washington by blacks, which culminated in Martin Luther King Jr.'s "I Have a Dream" speech, focused national attention on the plight of minorities and helped spur passage of the landmark Civil Rights Act of 1964.
But not all rallies reshape public attitudes. Mr. Rubenstein points to some of the labor marches of the 1980s as beginning and ending "at that moment" because national sentiment was not on their side at the time.
The frequency of marches in the 1980s and '90s has also diluted the impact of some protests. Nevertheless, depending on the message and the group, rallies like this Saturday's "Stand in the Gap: A Sacred Assembly for Men" can still become seminal events, touching the lives of millions of Americans.