Donald J Trump swept into Washington, DC on Thursday on the eve of his inauguration as the 45th president of the US and pledged to unify America as he addressed cheering supporters.

"It's a movement like we've never seen anywhere in the world ... it’s something that’s very very special," the president-elect declared at the celebratory evening concert on Thursday night.

 “I’m just the messenger,” he began.

“This started out tonight of being a small little concert and then we thought of the idea of doing it in front of the Lincoln Memorial and people came by their thousands and thousands and here we are tonight, all the way back.

“The phrase, you all know it, half of you’re wearing the hat: Make America Great Again,” said Trump.

Pledging to bring back jobs, build up the military and strengthen the border, he added: "We're going to do things that haven't been done for our country for many, many decades.

"It's going to change, I promise you. It's going to change."

"I'll see you tomorrow," he called out, and then fireworks exploded into the evening sky.

Among attendees at the two-hour event were his family, actor Jon Voight and Soul Man singer Sam Moore, a BBC report said.

The Make America Great Again! Welcome Celebration was open to the public and featured performances by country stars Toby Keith and Lee Greenwood.

Trump earlier laid a wreath at Arlington National Cemetery, Virginia.

Trump has asked about 50 senior Obama administration officials to stay on until they are replaced, spokesman Sean Spicer told a news conference, the report said.

They include Brett McGurk, the special envoy to the US-led coalition fighting the so-called Islamic State, as well as Deputy Defence Secretary Robert Work.

Meanwhile at the White House, President Barack Obama spent his last day in office with the daily briefing and lunch with Vice-President Joe Biden.

Obama also spoke to German Chancellor Angela Merkel in his final conversation with a foreign leader as president, according to the White House.

Inauguration events will run through the weekend. Some of the festivities will be taking place amid several organized protests, including the Women’s March on Washington, which is expected to draw about 200,000 people on Saturday.

Official inauguration events over the weekend:

January 20

9:30 am — Musical guests begin performing

11:30 am to 12:30 pm — Inaugural Swearing-in Ceremony
Opening remarks begin at 11:30 am and religious leaders will offer prayers and readings. Then, Mike Pence will be sworn in as vice president by Supreme Court Justice Clarence Thomas and Trump will be sworn in as president by Supreme Court Chief Justice John Roberts.

3 pm to 5 pm — Inaugural Parade
Trump will participate in the presidential procession and inaugural parade on Pennsylvania Avenue.

7 pm — Inaugural balls

January 21

10 am to 11 am — National Prayer Service
Trump and Pence will participate in an interfaith prayer service at Washington’s National Cathedral.