Donald J. Trump, the businessman and former reality television star, was sworn in Friday as the 45th president of the United States, promising to put "America first."
Under overcast skies and the U.S. Capitol, Trump took the oath of office from Supreme Court Chief Justice John Roberts.
"This is your day. This is your celebration. And this, the United States of America, is your country," Trump declared. "The oath of office I take today is an oath of allegiance to all Americans."
"From this day forward, it's going to be only America first, America first," he asserted. "Every decision on trade, on taxes, on immigration, on foreign affairs will be made to benefit American workers and American families. We must protect our borders from the ravages of other countries making our product, stealing our companies and destroying our jobs."
He added: "Protection will lead to great prosperity and strength. I will fight for you with every breathe in my body and I will never ever let you down."
Trump started his improbable presidential bid in 2015, beating out a former secretary of state and several senators and governors during his dizzying, chaotic rise to the White House. He becomes the first U.S. president with no prior government or military experience.
Trump, 70, was sworn in using two Bibles, the one used by Abraham Lincoln at his first inauguration and his own. Trump's mother gave him his personal Bible shortly before his ninth birthday, according to the inaugural committee.
Associate Justice Clarence Thomas swore in Vice President Mike Pence.
Wearing a red tie, Trump walked onto the dais, greeted his own family and Barack and Michelle Obama but did not acknowledge the former presidents and his former opponent, Hillary Clinton, who stood behind him to his left.
The crowd gathered for Trump's inauguration filled out only parts of the National Mall, smaller than the overflowing audience seen at Obama's first inauguration in 2009.
Trump is the most unpopular incoming president in recent memory, as only 38 percent of Americans view him positively and 48 percent view him negatively, according to NBC/Wall Street Journal polling. Obama, George W. Bush, and Bill Clinton had favorable ratings of 67 percent, 50 percent and 64 percent, respectively, as they took office.
Dozens of Democratic lawmakers said they would skip the inauguration, with some citing Trump's divisive policies and others citing the intelligence community's conclusion that Russia interfered in the 2016 election.
Mostly peaceful protests took place early on in Washington during Trump's Inauguration Day. But they became more violent throughout the day and at least 95 people were arrested.