WASHINGTON — One word could describe visitors to the Capitol Fourth Concert Wednesday night: sweaty.

Despite high temperatures and the threat of thunderstorms, thousands of visitors from across the continent took part in Independence Day celebrations in the nation's capital.

Hosting the 32nd annual Capitol Fourth, "Dancing with the Stars'" Tom Bergeron told the audience how he was feeling the heat, exclaiming at one point that he was "sweating standing still."

But few at the event were "standing still."

Megan Hilty kicked off the action with a performance that included back up dancers dressed like a Barbershop quartet. Amber Riley, of "Glee," got audience members to their feet, clapping and dancing to "Proud Mary." Broadway actors Matthew Broderick and Kelli O'Hara performed some subtle moves of their own in a duet. Even Phillip Phillips added some energy to the single that made him an American Idol, "Home."

Other performers included singer-songwriter Javier Colon; country music star Josh Turner; R&B performers Kool & the Gang; singer Russell Watson; the National Symphony Orchestra; Olympic medalist Apolo Anton Ohno with a tribute to the U.S. Olympic and Paralympic teams; and Academy-Award winning conductor John Williams.

Despite the heat, the usual enormous crowds flocked to the Mall and monuments throughout the day. By 7 p.m., the lawn of the Capitol where the concert took place was about two-thirds filled. Men and women lined the steps of the Capitol building and filled the balconies.

The Capitol Fourth Concert started at 8 p.m., ending about an hour and a half later as the fireworks disappeared behind the Washington Monument, set just beyond the show's Jumbotrons.

The National Park Service urged those attending to use public transportation to avoid traffic during the holiday.

Unlike in years past, the Smithsonian Metro Station – the station closest to the Mall – remained open until after the display, when it was limited to incoming passengers.

Park Police spokesman Sgt. Paul Brooks said the high temperature was one of the main concerns this year. The heat index, or how hot it felt, on the National Mall was 100 degrees Wednesday afternoon.

Washington boasted a variety of events during the day including the annual parade and a role-playing of the signing of the Declaration of Independence at the Jefferson Memorial.

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    Fireworks light the sky over the U.S. Capitol, left, Washington Monument and Lincoln Memorial in Washington on Wednesday, July 4, 2012, as seen from Arlington, Va.

  • July 4, 2012

    Fireworks light the sky over the U.S. Capitol, left, Washington Monument and Lincoln Memorial in Washington on Wednesday, July 4, 2012, as seen from Arlington, Va.

  • July 4, 2012

    Fireworks light up the sky over the Lincoln Memorial, Washington Monument, and the U.S. Capitol on July 4, 2012 in Washington, D.C. July 4th is a national holiday with the nation celebrating its 237th birthday.

  • July 4, 2012

    Fireworks light up the sky over the Lincoln Memorial, Washington Monument, and the U.S. Capitol on July 4, 2012, in Washington, D.C. July 4th is a national holiday with the nation celebrating its 237th birthday.

  • July 4, 2012

    Fireworks light up the sky over the Lincoln Memorial, Washington Monument, and the U.S. Capitol on July 4, 2012, in Washington, D.C. July 4th is a national holiday with the nation celebrating its 237th birthday.

  • July 4, 2012

    Fireworks illuminate the sky over the Washington Monument and Capitol Dome (bottom) during Fourth of July celebrations in Washington, D.C, on July 4, 2012. Independence Day, commonly known as the Fourth of July, is a federal holiday in US commemorating the adoption of the Declaration of Independence on July 4, 1776, declaring independence from the Kingdom of Great Britain.

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    Victoria Kiely of Ireland wears a 'USA' hat as she and others wait outside the Lincoln Memorial to watch fireworks in celebration of Fourth of July in Washington, D.C., on July 4, 2012. Independence Day, commonly known as the Fourth of July, is a federal holiday in US commemorating the adoption of the Declaration of Independence on July 4, 1776, declaring independence from the Kingdom of Great Britain.

  • July 4, 2012

    President Barack Obama speaks from the the Balcony of the White House as he and first lady Michelle Obama start an Independence Day celebration with a barbecue, concert and a view of fireworks, Wednesday, July 4, 2012, on the South Lawn of the White House in Washington.

  • July 4, 2012

    President Barack Obama speaks from the White House balcony as he and first lady Michelle Obama start an Independence Day celebration with a barbecue, concert and a view of fireworks, Wednesday, July 4, 2012, on the South Lawn of the White House in Washington.

  • July 4, 2012

    People gather at the Lincoln Memorial to watch fireworks in celebration of Fourth of July in Washington, D.C., on July 4, 2012. Independence Day, commonly known as the Fourth of July, is a federal holiday in U.S. commemorating the adoption of the Declaration of Independence on July 4, 1776, declaring independence from the Kingdom of Great Britain.

  • July 4, 2012

    U.S. President Barack Obama and First Lady Michelle Obama arrive for an Independence Day celebration, including a barbeque, concert and a view of fireworks for military members and their families and members of the administration the South Lawn of the White House in Washington, D.C., July 4, 2012.

  • July 4, 2012

    People gather at the Lincoln Memorial to watch fireworks in celebration of Fourth of July in Washington, DC, on July 4, 2012. Independence Day, commonly known as the Fourth of July, is a federal holiday in U.S. commemorating the adoption of the Declaration of Independence on July 4, 1776, declaring independence from the Kingdom of Great Britain.

  • July 4th, 2012

    Shirts off and sitting under a tarp Brandon List of Falls Church, Va., sits with Elena Villa, 2, as they try to resist the heat, while waiting for the start of the Independence Day fireworks celebration over the National Mall in Washington from their vantage point across the river in Arlington, Va., Wednesday, July 4, 2012.

  • July 4, 2012

    Emmarie Bonnia, 3, left, and Arhiana Bonilla, 4, enjoy cupcakes as they wait with their families to view the Independence Day fireworks celebration over the National Mall in Washington from their vantage point across the river in in Arlington, Va., Wednesday, July 4, 2012.

  • July 4, 2012

    Daniel Bonilla, 10, from Centerville, Va., has water poured on his head to beat the hot weather as he waits to view the Independence Day fireworks celebration over the National Mall in Washington, from their vantage point across the river in in Arlington, Va., Wednesday, July 4, 2012. (AP Photo/Alex Brandon)

  • July 4, 2012

    Nathaniel Sampson, 11, from Potomac, Va., pours cold water on the head of Alessio Humerez 10, from Alexandria, Va., to beat the hot weather as they wait to view the Independence Day fireworks celebration on the National Mall in Washington, from their vantage point across the river in in Arlington, Va., Wednesday, July 4, 2012. in Arlington, Va. (AP Photo/Alex Brandon)

  • July 4, 2012

    A military service member and his daughter watch as President Barack Obama and first lady Michelle Obama welcome guests to an Independence Day celebration with a barbecue, concert and a view of fireworks, Wednesday, July 4, 2012, on the South Lawn of the White House in Washington.