President Donald Trump assumed power Friday with a fiercely nationalistic vow to put "America first," taking a stinging swipe at the legacy of his predecessor hours after reciting the oath of office.
Hundreds of thousands of people stood on the rain-splattered National Mall to see the 70-year-old Republican billionaire be sworn in, and deliver a stridently populist call-to-arms.
Trump promised to lift up the nation's disenfranchised and those who felt betrayed by the political elites, declaring with vindication that "the forgotten men and women of our country will be forgotten no longer."
"From this day forward, a new vision will govern our land," Trump said, promising an end to business-as-usual in Washington. "From this moment on, it's going to be only America First."
Adhering to his vow to immediately start dismantling the healthcare reforms passed by outgoing president Barack Obama, Trump signed his first executive order in the Oval Office, targeting Obamacare.
It commands government offices to grant all possible exemptions to limit the "economic and regulatory burden" of the Affordable Care Act, as a prelude to a full repeal.
As the day's ceremonial rituals drew to a close, Trump and his wife Melania stepped out -- the first lady stunning in an off-the-shoulder ivory gown -- to lead the dance at one of the string of glitzy inaugural balls being held across the capital.
The pair slow-danced in a close embrace to a version of Frank Sinatra's "My Way," before they were joined by Vice-president Mike Pence and his wife Karen, and both families' children.
"Well, we did it," Trump told the revelers. "We won. And today, we had a great day."
"This was a movement. And now the work begins."
At another ball, Trump echoed his campaign pledge to help create lots of industrial jobs in the United States.
"We will not be taken advantage of any more. We're going to have those great companies come pouring back in," Trump promised again.
"We are not going to let you down. Remember the theme: Make America Great Again... Greater than ever before -- it will happen."
Power to the people
During his inaugural address, Trump vowed that his presidency would usher in a new political era.
"We are transferring power from Washington, DC, and giving it back to you, the people," he said.
Moments earlier, the incoming US leader had placed his left hand on a bible used by Abraham Lincoln and recited the 35-word oath spoken since George Washington.
The popular turnout was visibly smaller than for Obama's two inaugurations, in 2009 and 2013, with sections of the mall and bleachers along the parade route left nearly empty.
Throngs of Trump's opponents also converged on Washington.
Most of their protests -- by an array of anti-racist, anti-war, feminist, LGBT, and pro-immigration groups -- were peaceful, but sporadic violence marred the day.
Several hundred masked, black-clad protesters carrying anarchist flags smashed windows, lit fires and scuffled with riot police blocks from the parade held in Trump's honor, with at least 217 people arrested for vandalism.
Even the peaceful protesters were intent on spoiling Trump's party -- letting out a deafening roar as the presidential limousine rolled past.
"Not my president! Not my president!" they yelled, as the pro-Trump crowd in nearby bleachers chanted "USA! USA!"
'This carnage stops here'
For Trump's critics, there was disbelief that a man who 19 months ago hosted "The Apprentice" reality TV show is now leader of the free world -- sworn in with a 37 percent approval rating, the lowest on record, according to a CBS News poll.
Public interest lawyer Renee Steinhagen, 61, came from New York to join the protests.
"I'm doing this to express resistance to the change that awaits us," she said. "This administration seems more extreme than any other. This is a simple act of resistance. It's better than staying at home."
Trump's inauguration caps the improbable rise of the Manhattan real estate magnate who has never before held elected office, or served in government or the military.
Rather than appealing to a desire to bridge political divides and lift Americans' gaze to the horizon, his first address to the nation was deeply unorthodox.
Trump painted parts of America as a dystopian hell, with mothers trapped in poverty and "rusted-out factories scattered like tombstones across the landscape."
"This American carnage stops right here and stops right now," he said.
It was a deliberate and striking contrast from the uplifting message of Obama, who was among the dignitaries in attendance.
Obama and his wife Michelle departed the Capitol by helicopter minutes after the swearing-in, turning a page on eight years of Democratic leadership in the White House.
The first two Trump cabinet members were sworn in after being confirmed Friday by the US Senate. Both are retired generals: Secretary of Defense James Mattis, and Homeland Security Secretary John Kelly.
For the next few weeks the White House plans a series of daily executive orders to roll back Obama's agenda.
Trump has also vowed to re-examine long-running alliances with Europe and in Asia.
"We will reinforce old alliances and form new ones and unite the civilized world against radical Islamic terrorism, which we will eradicate completely from the face of the Earth."