Almost 78 days after one of the most tumultuous political elections in history, Joe Biden has been sworn in as the 46th President of the United States.

• Click through to the LIVE BLOG to see how the Inauguration Day ceremony is unfolding.

At this hour, my friends, democracy has prevailed’’
– President Joe Biden

With his hand on an heirloom Bible that has been in his family for more than a century, Mr Biden took the presidential oath of office administered by US Chief Justice John Roberts.

The 78-year-old vowed to “preserve, protect and defend the Constitution of the United States”.

“Through a crucible for the ages, America has been tested anew, and America has risen to the challenge,” the new US President said as he began his inaugural address.

Joe Biden and Kamala Harris attend a wreath-laying ceremony at Arlington National Cemetery’s Tomb of the Unknown Soldier after the Inauguration ceremony. Photo: Getty

“Today we celebrate the triumph not of a candidate but of a cause: the cause of democracy.”

He was greeted by members of the US military who lined the White House driveway as the 46th president and first lady walked out to the main entrance under the North Portico.

As the couple looked out from the grounds of the White House, a band played “Hail to the Chief” and “God Bless America”.

Mr Biden pledged during his inauguration speech to be honest with the country as it continues to confront its health, economic and inequality challenges, adding that leaders have an obligation “to defend the truth and defeat the lies”.

He asked even those who did not vote for him to give him a chance.

“Hear me out as we move forward,” he said, adding he would “fight as hard for those who did not support me as for those who did”.

We must end this uncivil war that pits red against blue.’’

Mr Biden said that his swearing-in marks a day of “history and hope”.

Joe Biden hugs his son Hunter Biden and daughter Ashley Biden after being sworn in. Photo: Getty

In calling for unity among Americans, Mr Biden said politics does not have to be a “raging” fire that destroys everything in its path.

Without directly naming Donald Trump, he called out the spread of toxic misinformation that has widened existing divisions in the US.

“We must reject the culture in which facts themselves are manipulated and even manufactured,” Mr Biden said.

“America has to be better than this. And I believe America is so much better than this.”

Mr Trump skipped the inauguration, becoming the first outgoing president in 152 years to not attend the swearing-in ceremony of his successor.

His now-former vice president Mike Pence, however, was in attendance.

Kamala Harris and husband Douglas Emhoff descend the steps of the East Front of the US Capitol with former vice president Mike Pence and wife Karen Pence. Photo: Getty

Mr Pence skipped Mr Trump’s farewell ceremony to be present at the inauguration with his wife, Karen.

Meanwhile, Mr Trump wished the new administration good luck and success from a military base in Maryland.

“I think they’ll have great success, they have the foundation to do something really spectacular,” he said, after leaving the White House for the last time.

COVID-19 ‘stalks the country’

During his inauguration speech, Mr Biden asked the millions of Americans who tuned in to share a moment of silent prayer in remembrance of those who lost their lives to COVID-19.

“Those 400,000 fellow Americans – mums, dads, husbands, wives, sons, daughters, friends, neighbours and coworkers. We’ll honour them and become the people and nation we know we can and should be,” Mr Biden said.

The coronavirus “silently stalks the country” and has cost more American lives than World War I, he said.

The inauguration of US President-elect Joe Biden on the West Front of the US Capitol. Photo: Getty

Few Americans “have found a time more challenging than the time we are in now”, he added.

“We’ll press forward with speed and urgency… We have much to do in this winter of peril and significant opportunities.”

‘Long live Kamala Harris’

Early Thursday morning (Australian time), Kamala Harris made history as the first black, South Asian and female US vice president.

Standing by her side was husband Doug Emhoff who officially became the first second gentleman of the United States.

In the Indian village of Thulasendrapuram, about 350 kilometres from the southern coastal city of Chennai, residents set off firecrackers and prayed at a Hindu temple as they watched Ms Harris, who has strong roots there, take her oath of office.

US Vice President-elect Kamala Harris is sworn in during the inauguration of Joe Biden. Photo: AAP

Groups of women in bright saris and men wearing white dhoti pants watched the inauguration live as reporters broadcast the villager’s celebrations to millions of Indians.

The villagers chanted “Long live Kamala Harris” while holding portraits of her and set off fireworks the moment she took the oath.

“We are feeling very proud that an Indian is being elected as the vice president of America,” said teacher Anukampa Madhavasimhan.

Unprecedented security

In the hours before the event, federal agents monitored “concerning online chatter”, including an array of threats against elected officials and discussions about ways to infiltrate the inauguration.

National Guard troops standby outside security fencing along Pennsylvania Avenue as Joe Biden’s motorcade drives past on its way to the Capitol. Photo: Getty

A beefed-up security force was on standby including thousands of troops in riot gear and armoured vehicles.

They lined the streets of Washington DC and concrete barriers blocked the empty streets around the US Capitol.

But the ceremony went off without a hitch. There were no crowds and no serious disruptions in the city.

More than 25,000 troops and police were called in for duty ahead of the ceremony.

Capitol Police officers stand along the abbreviated parade route following the inauguration. Photo: Getty

The unprecedented precautions ensured that Mr Biden and Ms Harris were safely sworn in.

“Just days after a riotous mob thought they could use violence to silence the will of the people, to stop the work of our democracy, to drive us from this sacred ground, it did not happen,” Mr Biden said in his speech.

“It will never happen. Not today. Not tomorrow, not ever, not ever.”

The increased security is likely to remain in the nation’s capital for at least a few more days.

-with AAP