At an event billed as nonpolitical but reflecting the mood of a sizable number in the country, the rally's marquee speaker, Sarah Palin, praised "patriots" in the audience for "knowing never to retreat."
The two champions of the tea party movement spoke from the very spot where Martin Luther King Jr. delivered his "I Have a Dream" speech 47 years ago. Some civil rights leaders who have denounced Beck's choice of a venue staged a rival rally to honor King.
Palin, the 2008 GOP vice presidential nominee who may make a White House run in 2012, said activists must honor King's legacy by paying tribute to the men and women who protect the United States in uniform.
Beck, pacing back and forth on the marble steps, said he was humbled by the size of the crowd, which stretched along the Washington Mall's long reflecting pool nearly all the way to the Washington Monument.
"Something beyond imagination is happening," he said. "America today begins to turn back to God."
"For too long, this country has wandered in darkness," said Beck, a Fox News host. He said it was now time to "concentrate on the good things in America, the things we have accomplished and the things we can do tomorrow."
Neither Beck nor Palin made overtly political comments. Palin, greeted by chants of "USA, USA, USA" from many in the crowd, told the gathering, "It is so humbling to get to be here with you today, patriots. You who are motivated and engaged ... and knowing never to retreat."
"We must restore America and restore her honor," said the former Alaska governor, echoing the name of the rally, "Restoring Honor."
Palin told the crowd she wasn't speaking as a politician. "No, something more, something much more. I've been asked to speak as the mother of a soldier and I am proud of that distinction. Say what you want to say about me, but I raised a combat vet and you can't take that away from me." It was a reference to her son, Track, 20, who served a yearlong deployment in Iraq.
Palin honored military members in her speech. She likened the rally participants to the civil rights activists who came to the National Mall to hear King's historic speech. She said the same spirit that helped civil rights activists overcome oppression, discrimination and violence would help this group as well.
"We are worried about what we face. Sometimes, our challenges seem insurmountable," Palin said.
"Look around you. You're not alone," Palin told participants. The crowd - organizers had a permit for 300,000 - was vast, with people standing shoulder to shoulder across large expanses of the Mall. The National Park Service stopped doing crowd counts in 1997 after the agency was accused of underestimating numbers for the 1995 Million Man March.
Civil rights leaders protested the event and scheduled a 3-mile plus march from a high school to the site of a planned King memorial near the Tidal Basin and not far from Beck's gathering.
Karen Watts, 57, of Mount Vernon, N.Y., was among those attending the King rally and march. "The dream is not forgotten," she said. "I live my life honoring Dr. King to make sure I'm part of that dream, by serving my community."
Of Beck's rally, she said, "They're American citizens. So long as they don't infringe upon my rights ... let them do what they do."
Eleanor Holmes Norton, Washington's delegate to Congress, said she remembers being at King's march on Washington, which she said prompted change and ended segregation in public places. "Glenn Beck's march will change nothing. But you can't blame Glenn Beck for his March-on-Washington envy," she said.
Beck has said he did not intend to choose the King anniversary for his rally but had since decided it was "divine providence."
Beck, in a taped presentation mixed in with his live remarks, invoked King's message and said "the fight for freedom was not easy." He repeatedly injected religion into the event and urged rally participants to rely on faith to help the U.S. recover from an economic recession that has given the country stubbornly high unemployment.
"Faith is in short supply," Beck said. "To restore America, we must restore ourselves."
Organizers said their aim was to honor military personnel and others "who embody our nation's founding principles of integrity, truth and honor."
Many in the crowd watched the proceedings on large television screens. On the edges of the Mall, vendors sold "Don't Tread on Me" flags, popular with tea party activists. Other activists distributed fliers urging voters "dump Obama." The pamphlet included a picture of the president with a Hitler-style mustache.
The Rev. Al Sharpton, leading the civil rights march and rally, mocked the Beck production. "The folks who used to criticize us for marching are trying to have a march themselves," he said. "We come because the dream has not been achieved. We've made a lot of progress. But we still have a long way to go."
He said he wasn't seeking a confrontation with those at the Beck rally.
"We wouldn't disgrace today by allowing you to provoke us," he said in remarks directed at the Beck followers. "If peopple start heckling, smile at them," he told fellow marchers.
People began filling up the space between the Lincoln Memorial and the Washington Monument early in the day, many waving American flags. Wasington's subway system was extremely crowded with long lines of people trying to get to the rally. Metro spokeswoman Lisa Farbstein said that there was crowding at least a dozen stations.
Ricky Thomas, 43, a SWAT team police officer from Chesapeake Beach, Md., brought his 10-year old son Chase to the Beck rally. "I wanted my son to see democracy in action," Thomas said.
He said he wants government to stay out of people's lives. He acknowledged that he works for government, but said it's "a part of government that helps people when they are in trouble."
Beck has given voice to those angry and frustrated with President Barack Obama and other Democrats this election year, especially members of the tea party movement.
Associated Press writers Brett Zongker, Nafeesa Syeed and Ricardo Alonso-Zaldivar contributed to this report.