Hundreds of thousands of protesters took to the streets in the nation's capital and cities across the country Saturday in protest of Donald Trump on the first full day of his presidency.

Dubbed the Women’s March on Washington, the event spurred by a Facebook page led to “sister marches” in major cities around the world, including Paris, London and Sydney.

More than 2.5 million people participated in marches across the U.S. on Saturday, according to a review of official and unofficial estimates from the nation's largest cities.

Large turnouts were reported in Boston, New York, Chicago and Los Angeles as organizers for the main rally and march in Washington, D.C., grappled with huge numbers of demonstrators.

A number of Democratic lawmakers also appeared at the rallies to speak in solidarity with the protesters in their home states.

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"It was amazing, the energy, the numbers, the variety of people," Rep. Luis Gutiérrez (D-Ill.), the first lawmaker to say he'd boycott Trump's inauguration, told The Hill.

"The people I met were marching for women's rights or health care, or Planned Parenthood or civil rights or immigrants and refugees, but there was no division or discord. They were all united in supporting human rights and it was just wonderful."

Rep. John Lewis (D-Ga.), whose boycott of Friday’s inauguration ceremony spurred backlash from Trump and saw dozens of other House Democrats skip the event, spoke to demonstrators in Atlanta on Saturday afternoon.

“I know something about marching,” the civil rights icon said to cheers from the crowd. “I marched from Selma to Montgomery. I’m ready to march again.”

Washington's march drew such a large crowd – reportedly upwards of 500,000 – that the proposed route to travel past the White House was altered.

But demonstrators still marched past a barricaded White House on Trump’s first full day in office, as protesters carried LGBT flags and signs with messages supporting abortion rights, the Black Lives Matter movement and criminal justice reform, among others issues.

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Trump, who was sworn into office on Friday, started the day by attending prayer services before trekking to the Central Intelligence Agency headquarters in Langley, Va., where he defended his support for the intelligence community.

During the CIA appearance, Trump boasted about the size of the crowds for his inauguration, dismissing media coverage that compared it to former President Barack Obama Barack Hussein ObamaThe Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon Trump appointees stymie recommendations to boost minority voting: report Obama's first presidential memoir, 'A Promised Land,' set for November release MORE's 2009 inauguration.

White House press secretary Sean Spicer also made his first appearance behind the lectern in the White House briefing room on Saturday afternoon, where he scolded media for its "shameful and wrong" focus on the inaugural crowd size.

"This was the largest audience to ever witness an inauguration, period, both in person and around the globe,” Spicer claimed.

Media outlets quickly pointed to photos and video showing fewer people assembled on the National Mall on Friday than were there for Obama's inauguration.

The combative showing came on the first full day of Trump's presidency. On Friday, Trump's first two Cabinet nominees were confirmed and sworn in and he signed an executive order targeting ObamaCare.

The D.C. Metro, which extended service to accommodate the influx of locals and out-of-town demonstrators taking part in the march, was packed with riders, many clad in pink, knitted hats.

The Saturday protests far outpaced the demonstrations in D.C. on Friday, when Trump was officially sworn in as commander in chief.

More than 200 people were arrested on the day of the inauguration and charged with rioting after trashcans were set on fire and storefront windows were smashed. Police vehicles were also damaged.

On Saturday, lawmakers and celebrities alike joined protesters in the District, with Sen. Tammy Duckworth (D-Ill.), Sen. Kirsten Gillibrand Kirsten GillibrandSuburban moms are going to decide the 2020 election Jon Stewart urges Congress to help veterans exposed to burn pits The Hill's Campaign Report: 19 years since 9/11 | Dem rival to Marjorie Taylor Greene drops out | Collin Peterson faces fight of his career | Court delivers blow to ex-felon voting rights in Florida MORE (D-N.Y.) and Sen. Cory Booker (D-N.J.) all making appearances.

Comedian Amy Schumer introduced Madonna, who made a surprise stop at the march to continue her criticisms of Trump.

"And to our detractors that insist that this march will never add up to anything, f--k you. F--k you,” the singer said in remarks carried live on MSNBC and CNN.

Multiple chants were repeated throughout the day, from "this is what democracy looks like" to "can't build the wall, hands too small."

Filmmaker Michael Moore also spoke at the rally, engaging the crowd by providing them a number to call Congress and having attendees repeat it back.

"It'll take two minutes. Each day, I and others are going to be posting things for you to call Congress to do," Moore said.

Many people were spotted gathering in front of the Trump International Hotel, booing and leaving their protest signs in front.

Sen. Elizabeth Warren Elizabeth WarrenWarren, Schumer introduce plan for next president to cancel ,000 in student debt The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon No new taxes for the ultra rich — fix bad tax policy instead MORE (D-Mass.) spoke to a crowd of marchers in the Boston Common, urging them to “fight back.”

“The fact is that the playing field has been tilted badly in favor of those at the top for a generation now,” Warren said. “And now, President Trump Donald John TrumpHR McMaster says president's policy to withdraw troops from Afghanistan is 'unwise' Cast of 'Parks and Rec' reunite for virtual town hall to address Wisconsin voters Biden says Trump should step down over coronavirus response MORE and the Republican Congress are ready to ram through laws that will tilt it even harder.”

– Rafael Bernal, Ali Breland, Sylvan Lane and Reid Wilson contributed

Updated: 8:06 p.m.