Four years ago on a rainy Washington day, Trump placed his left hand on an old Bible, raised his right hand and took the oath of public office at the West Front of the US Capitol.

In his first public speech as the 46th president of the United States, Joe Biden needs to begin to heal the "American carnage" that Donald Trump four years ago promised to fix but ended up exacerbating.

I watched on as Trump placed his left hand on an old Bible on that rainy inauguration day in 2017, raised his right hand and took the oath of public office at the West Front of the US Capitol.

Donald Trump takes the oath of office as Melania Trump, looks on during the presidential inauguration in January, 2017. Bloomberg.

"I, Donald John Trump, do solemnly swear that I will faithfully execute the office of President of the United States, and will to the best of my ability, preserve, protect and defend the constitution of the United States,” Trump pledged to Chief Justice John G Roberts jnr.

Egged on by thousands of supporters wearing red "Make America Great Again" hats and with outgoing president Barack Obama seated nearby, Trump vowed the "American carnage stops right here and stops right now".

He and his wife, Melania, won't welcome Biden and his wife, Jill, to the White House, as the Obamas did for the Trumps.

Michelle Obama, left, and Barack Obama, right, welcomed Melania and Donald Trump to the White House for Trump's inauguration in 2017. Bloomberg.

Donald Trump granted clemency to 143 allies and friends in his last hours as president including former strategist Steve Bannon; Joe Biden's first act as President-elect was to attend a ceremony for America's COVID-19 dead.