WASHINGTON – The capital braced for an inaugural extravaganza today under a blanket of wet snow that has caused fender benders and traffic snarls in a city already coping with street closures spanning 100 square city blocks.

The weather and pervasive security presence did not keep thousands of people from gathering on the National Mall to hear the president speak under a cascade of fireworks.

Addressing a crowd of about 50,000 people at the Ellipse south of the White House, Mr. Bush called for unity. “We are one America, and every day that I am your president, I will serve all Americans,” he said.

At a concert titled “A Celebration of Freedom,” Mr. Bush spoke of freedom as the central theme of his presidency. A preview of the inaugural address he is to deliver at noon promised a similar tone.

“We are led, by events and common sense, to one conclusion: The survival of liberty in our land increasingly depends on the success of liberty in other lands. The best hope for peace in our world is the expansion of freedom in all the world,” Mr. Bush will say, according to a partial copy of the speech released yesterday.

The streets around the National Mall flashed with the red and blue lights of police cars yesterday, and helicopters hovered against a chalky sky. Portable lavatories lined the downtown streets on which cars, pedestrians, and caravans of tour buses slipped and slid through brown slush.

“It’s so cold,” howled Raheem Weir, a 24-year-old trumpet player in the Ohio State University Marching Band who will be performing in today’s parade, as he walked toward Pennsylvania Avenue yesterday. “But it’s not something you can pass up. It’s a once-in-a-lifetime opportunity.”

“We just wanted to say we were here as part of history,” said Jackie Turner, a 41-year-old registered nurse who came from Bedford, Ind., to watch the president be sworn in and deliver his inaugural address.

“I want to hear the president say that he is ready to tackle the tough issues, now that he no longer has to run for reelection. I want to hear that everyone will work together to get things done,” she said.

The committee organizing the official events expects 250,000 people to attend the swearing-in and 100,000 to attend the parade. Later today, 55,000 people are expected to dance and drink at the numerous inaugural balls around the city.

A 51-year-old school-system worker from Wichita Falls, Texas, Brenda Williams, said she made the trek to the capital for one simple reason: “To see George Bush. We love him.”

The sleet and snow, “has slowed us down, but it has not stopped us,” said her companion, Anne Morgan, a 57-year-old retiree.

The concert was emceed by the host of the television show “American Idol,” Ryan Seacrest, and it featured performances by Andrea Bocelli, Patti LaBelle, the Gatlin Brothers, and the Rockettes. Former astronauts, including Buzz Aldrin, were also in attendance.

Earlier in the day, the president and the first lady, Laura Bush, toured the rotunda of the U.S. Archives, viewing the Declaration of Independence, the U.S. Constitution, the Bill of Rights, and George Washington’s handwritten first inaugural address. They also saw the Bible used by Washington in his inauguration.

Mr. Bush told reporters he felt the historical significance of the moment.

The president had gone through 21 revisions of his remarks as of yesterday afternoon, according to the White House spokesman, Scott McClellan. His speech is expected to be 17 minutes, he said, and it will address the themes of freedom in foreign and domestic policy.

Mr. Bush will be taking the oath on the Bush family Bible, Mr. McLellan said. Mr. Bush used the same Bible in his 2001 inauguration, and it has also been used by his brother, Jeb Bush, when he was sworn in as governor of Florida. The president’s father, President George H.W. Bush, used that Bible along with the original Bible used by George Washington during his inauguration.

Mr. McClellan said Mr. Bush wanted to use the Washington Bible in 2001, but he did not out of concern that weather conditions could harm it.

Today’s ceremony will also include an invocation and a benediction delivered by ministers, despite an attempt by atheist lawyer Michael Newdow to have the Supreme Court prevent the recitation of prayers. Mr. Newdow, who has also tried to have the court remove the words “under God” from the Pledge of Allegiance, alleged that reading the prayer would violate the Constitution by allowing the government to imposing religious beliefs.

Chief Justice Rehnquist, who is slated to administer today’s oath, denied that claim yesterday without comment. Prayers have traditionally been a part of inaugurations.

Despite the heavy tourist draw, some Washingtonians have complained that the city was being asked for the first time to cover the $11.9 million costs of security for the event.

Washington’s mayor, Anthony Williams, criticized the Bush administration for refusing to reimburse the city, which will spend money earmarked for the capital’s homeland security funds. He said the funds should be set aside for emergency preparedness.

Over 6,000 law enforcement officers will be out in force, according to the Secret Service. On Tuesday, police faced off with a man threatening to blow up his van in an incident that was unrelated to the inauguration or to terrorism.

Yesterday, there were no unusual events, according to the Secret Service.

“Thus far, things have been running well,” said a spokesman for the service, Tom Mazur.

Authorities have banned items ranging from backpacks and sign supports to pets from the inaugural sites. Special restrictions were also put on the airspace above the city and the waterways that surround it.

The president’s remarks yesterday were followed by a canopy of fireworks fired from 10,000 mortar tubes. The fireworks crews had to overcome delays due to snowy road conditions that hampered transportation of large equipment, said a former New York congressman, Felix Grucci, whose company set up the display.

Despite the weather, they went off in spectacular fashion. Mr. Grucci’s next stop, he said, will be the West Palm Beach wedding of Donald Trump and model Malania Knauss. The display, he said, will be “only” about half as big as the inaugural show.