U.S. President Donald Trump points to the stands as he walks with his wife Melania during the Inaugural Parade in Washington, Jan. 20, 2017.
U.S. President Donald Trump points to the stands as he walks with his wife Melania during the Inaugural Parade in Washington, Jan. 20, 2017.

WASHINGTON - Billionaire real estate mogul Donald Trump, sworn in Friday as the 45th U.S. president, said that he will invoke "a new vision" for America, one where workers abandoned by shuttered factories and diminished economic fortunes will not be forgotten.

"This moment is your moment, it belongs to you," Trump told several hundred thousand people gathered on the National Mall in Washington to watch his swearing-in and inaugural address. "The people become the rulers of this nation again."

As a light rain fell, the 70-year-old Trump, now the oldest-ever U.S. chief executive, said, "A new vision will govern us from this day forward. It's only going to be America first. I will never ever let you down. America will start winning, winning like never before."

A short time later, as Trump was hosted by congressional leaders at a lavish luncheon, protests against him erupted in parts of downtown Washington several blocks from the inaugural parade route. Rock-throwing demonstrators clashed with police, who said more than 95 of the protesters were arrested.

In echoes from his long campaign for the White House, the Republican Trump painted a picture of workers who have been left behind in the world's largest economy, buffeted by global economic changes they have been powerless to overcome.

It was these voters who gave him the edge in key states, U.S. political analysts say, to hand him an unexpected win in the November election over Democrat Hillary Clinton, a former U.S. secretary of state who watched from a nearby seat at the U.S. Capitol as he became the American leader.

WATCH: Trump takes the oath of office

"Washington flourished but the people did not share in its wealth," Trump said. "Politicians prospered but the jobs left and the factories closed."

"This American carnage stops right here and right now," he declared.

Trump vowed to restore jobs lost to overseas ventures, while boosting U.S. employment with reconstruction of the country's deteriorating roads, bridges and other infrastructure.

"So to all Americans, hear these words," he said. "You will never be ignored again."

Trump touched only briefly on U.S. foreign policies, saying that America would seek friendship with the world while recognizing that countries abroad had a right to govern themselves as they see fit.

He  said the United States would "shine for everyone to follow."

But he renewed his frequent vow to attack "radical Islamic terrorism," saying he would "eradicate [it] completely from the face of the earth."  

He took the traditional, time-honored oath, swearing as past presidents have, to "preserve, protect and defend the Constitution of the United States." Trump replaces now former President Barack Obama, who leaves office after two terms in the White House.

The throng on the Mall was large, but did not appear to be as big as when Obama first took office in 2009.

Many of those who witnessed Trump's assumption of power wore hats with Trump's trademark campaign slogan, "Make America Great Again,” cheering loudly when he officially became president.

Trump took the oath of office from Supreme Court Chief Justice John Roberts, with a hand on two Bibles, one from his youth and one used by a 19th-century U.S. president, Abraham Lincoln, the American leader during the country’s Civil War.

Shortly before, former Indiana Governor Mike Pence took the oath of office as the new vice president, replacing Joe Biden.

After Trump's inaugural address, congressional leaders hosted Trump, his wife, Melania, Vice President Pence, his wife, Karen, and their families at a lavish luncheon before the start of the inaugural parade down Pennsylvania Avenue to the White House, Trump's new home.

In Photos: Inauguration Day

View full gallery

The new president's day started with the traditional Inauguration Day service at St. John's Church near the White House.

The Trumps then headed across Lafayette Square to the White House for a quiet tea and get-together with Obama and first lady Michelle Obama as they prepared to leave the home where they have lived for the past eight years.

The Obamas and Trumps later traveled together to the U.S. Capitol for the inauguration.

Trump's inauguration heralds a marked change in the Washington political landscape, with Republicans jointly controlling Congress and now the White House for the first time in more than a decade.

But Trump's favorability rating stands at about 40 percent, according to national polls, the lowest for any incoming president in decades.

The new president and like-minded conservative Republican lawmakers have vowed to overturn many of the signature policies of Obama, a Democrat, including his health care reforms, environmental regulations and business restrictions.

Numerous contentious legislative disputes are expected, though, leaving the eventual outcome in doubt.

In Photos: Anti-Trump protests

View full gallery

Trump pledges

On the international front, Trump has pledged to build a wall on the U.S. southern border with Mexico, toughen the U.S. fight against Islamic terrorists in the Middle East, and ease relations with Russia and President Vladimir Putin.

Anti-Trump protesters, however, are demonstrating against his inauguration.

Protesters appeared Friday at National Mall security checkpoints, sometimes slowing visitors from reaching their vantage points, presaging the street protests after Trump's inauguration.

By mid-afternoon, several thousand protesters had gathered several blocks north of the National Mall, with Washington, D.C., police saying they had arrested 95 people after several clashes, some in which protesters broke store and car windows, and set trash cans on fire. Police also used chemical spray against the protesters.

On Thursday night, rowdy protesters clashed with police outside the National Press Club in Washington where a pre-inauguration cocktail event called the "Deploraball" was taking place.

Protesters yelled "No Trump. No fascist USA!" as police tried to keep them away from the building's doors. Some protesters threw objects at police. At least one fire was set in the street. Officers deployed chemical spray at the crowd.

Former President Barack Obama and his wife Michell
Former President Barack Obama and his wife Michelle stand with President Donald Trump and first lady Melania Trump during a departure ceremony on the East Front of the U.S. Capitol in Washington, Jan. 20, 2017, after Trump was inaugurated.

A watchdog group, Citizens for Responsibility and Ethics in Washington, alleged that with Trump's inauguration, he was in immediate violation of a constitutional provision banning payments to presidents from foreign governments.

The dispute stems from Trump's ownership of a luxury hotel in Washington that is frequented by foreign officials visiting the U.S. capital, although Trump's lawyer says any profits from their stays at the hotel will be donated to the U.S. Treasury.

Trump's journey to the White House marks one of the most unusual paths to political prominence in American history.

Just a year and a half ago, he descended from an escalator at Trump Tower in New York City, the luxury skyscraper he built and where he has lived for years, to make the improbable declaration that he was running for president.

The announcement was greeted by some U.S. political figures and media pundits with derision; analysts said there was only a minuscule chance that Trump would wind up as the Republican party's choice to succeed Obama, let alone to replace him in the White House.

Arduous journey

Over the course of a contentious and often bitter year of campaigning, however, Trump triumphed over 16 other Republican candidates, almost all of them "professional" politicians — current or former senators or governors.

Trump disparaged his opponents with belittling, schoolyard taunts and then handily beat them at the ballot box in state-by-state party primaries and caucuses.

Former President George W. Bush, right, his wife L
Former President George W. Bush, right, his wife Laura, Former Secretary of State Hillary Clinton and Former President Bill Clinton wait for the 58th Presidential Inauguration for President-elect Donald Trump at the U.S. Capitol in Washington, Jan. 20, 20

And then he won November's national election against Clinton, who was looking to become the country's first female president.

Clinton, the wife of former President Bill Clinton, said in a Twitter comment that she attended Trump's inauguration to "honor our democracy & its enduring values."

The moment was perhaps bittersweet for her. She won nearly 3 million more votes than Trump in the national popular vote count, but Trump won where it mattered, in the Electoral College, the U.S. system of picking its presidents, where the state-by-state outcomes determine the winner.

Trump is the first U.S. president who has never held elective office beforehand, been appointed to a government position or served in its military.

Instead, Trump has spent a life building skyscrapers in New York and elsewhere. He has erected casinos along the Atlantic Ocean, bought an airline and peddled steaks, wine and other products, all with his name branded on them.

He wrote a best-selling book about his real-estate deals and hosted a reality-television game show, The Apprentice, that judged contestants' business skills. As the host, Trump famously told losers of the game: "You're fired!"

Global reaction to Trump's inauguration