Hundreds of thousands gathering for 'historic' Donald Trump inauguration

Ebullient Trump supporters are flocking to the capital for the inaugural festivities, some wearing red hats emblazoned with his "Make America Great Again" campaign slogan.

But in a sign of deep divisions sowed during his combative campaign, dozens of Democratic legislators are boycotting the swearing-in ceremony on Capitol Hill.

While Mr Trump came to power bucking convention, he wrapped himself in the traditional pomp and pageantry that accompanies the peaceful transfer of power.

The president-in-waiting will attend church with his family, then meet President Barack Obama and first lady Michelle Obama for tea at the White House.

The Trumps and the Obamas will travel together in the presidential limousine for the short trip to the Capitol for the swearing-in ceremony.

Trump supporters started lining up at security checkpoints before dawn to take their places on the National Mall for the quadrennial rite of democracy.

Protesters were also out early, some wearing orange jumpsuits with black hoods over their faces.

Trump aides said the president-elect had been personally involved in crafting his inaugural address, a relatively brief 20-minute speech to a crowd of hundreds of thousands, expected to centre on his vision for what it means to be an American.

Spokesman Sean Spicer said the address would be "less of an agenda and more of a philosophical document".

Mr Trump has pledged to upend Mr Obama's major domestic and national security policies, including repealing his signature health care law and building a wall along the US-Mexico border.

But he has offered few details of how he plans to accomplish his agenda, often sending contradictory signals.

The three days of inaugural festivities kicked off on Thursday. The president-elect left his Trump-branded jet in New York and flew to Washington in a government plane, saluting an Air Force officer as he descended the steps with his wife, Melania.

He and the incoming vice president, Mike Pence, laid a wreath at Arlington National Cemetery before joining supporters for an evening concert at the Lincoln Memorial.

"We're going to unify our country," he said at the close of the two-hour concert featuring country star Toby Keith, soul's Sam Moore and the Piano Guys. But not singer Jennifer Holliday: She backed out after an outcry from Trump critics.

With rain a possibility, the National Park Service announced it was easing its "no umbrella" policy, allowing collapsible umbrellas along the parade route and on the National Mall.

The nation's soon-to-be president joked about the chance of a downpour. "That's okay," he told campaign donors at an event on Thursday night, "because people will realise it's my real hair.

"Might be a mess, but they're going to see that it's my real hair."

All of the living American presidents are scheduled to attend the swearing-in ceremony, except for 92-year-old George HW Bush, who was taken to hospital this week with pneumonia. His wife Barbara was also admitted to hospital after falling ill.

Mr Trump tweeted his well-wishes to the Bushes, saying he was "looking forward to a speedy recovery".

Hillary Clinton, Mr Trump's vanquished campaign rival, also plans to join dignitaries at Capitol Hill.

While Mr Trump revels in a celebratory lunch with legislators and a parade down Pennsylvania Avenue - passing his newly opened Washington hotel - workers at the White House will set about the process of moving out the Obamas and preparing the residence for its new occupants. Moving trucks were on standby at the White House.

Mr Obama, who will continue to live in Washington, is leaving town with his family after the inauguration for a vacation in Palm Springs, California. He plans to address a farewell gathering of staff at Joint Base Andrews before boarding his last flight on the military aircraft that ferries presidents on their travels.