Buses are shuttling in anti-abortion protesters from all over the country for the annual March for Life.
Organizers predict many of them will be young people rallied by church groups and social media.
Pope Benedict sent them his encouragement by way his personal Twitter account,@pontifex : "I join all those marching for life from afar, and pray that political leaders will protect the unborn and promote a culture of life," he posted early Friday morning.
"We are expecting record-breaking crowds - 80% under the age of 20," said Jeanne Monahan, president of the March for Life Education & Defense Fund. "Mostly teenagers come and we get a lot of high school groups."
This is Monahan's first year leading the march. She predicts the event will be different from past years.
"It's a pretty big event to pull off - the planning for next year's march started last week," Monahan said.
Nellie Gray, who had led the anti-abortion demonstrators every year since the Roe v. Wade decision legalized abortion in 1973, died in August at age 88.
"We want to appeal to the younger crowd, so we made big changes," Monahan said. "We shortened the program from longer than two hours to an hour, picked speakers who are more engaging and we are deeply engaging social media."
According to a recent Pew Research Center poll, 37% of Americans do not know that Roe v. Wade dealt with the issue of abortion. Among the age group targeted by the March for Life, the number is higher - 57% of adults under age 30 don't know what the case is about.
Americans remain divided on abortion, according to a recent USA TODAY/Gallup Poll.
Significantly more Americans - 53% to 29% - want the decision kept in place rather than overturned. Another 18% have no opinion, the highest level of uncertainty Gallup has recorded on the issue.
Sydney Goldstein, 16, of Charlotte, is heading to the march with about 30 students from her government class at Charlotte Christian School.
"I am going to speak for the babies that are dying every day that don't have a voice to speak for themselves," Goldstein said.
"This is one way to voice my opinion because I cannot vote."
Friday's rally will begin before noon on the Mall and around 1:15 p.m. the march will begin and follow its traditional route up Constitution Avenue to the Supreme Court building on Capitol Hill.
Speakers include Sen. Rand Paul, R-Ky., and Rep. Diane Black, R-Tenn.
Benedictine College has sent seven full buses - nearly 400 people - for a 30-hour ride from Atchison, Kan., to Washington, D.C., for the march.
This is the largest group to go in the school's 28 years of involvement, spokesman Humam AlMukhtar said.
(Copyright © 2013 USA TODAY)