Joe Biden has been sworn in as the 46th President of the United States.
The ceremony took place in a quieter Washington where spectators have been replaced by a sea of flags.
President Biden has issued a unifying message as he made his inaugural address:
"From now, on this hallowed ground where just a few days ago, violence sought to shake the capitol's very foundation, we come together as one nation under god, indivisible, to carry out the peaceful transfer of power, as we have for more than two centuries."
Shortly before President Biden took his oath, Kamala Harris was sworn in as the first female, first black, and first South Asian Vice President.
Lady Gaga performed The National Anthem after campaigning for Mr Biden.
Joe Biden has never shyed away from telling people about his Irish roots.
The 46th President of the United States has family ties to County Louth, and County Mayo.
He is the 23rd US President to claim Irish ancestry.
Throughout his life, he has always been keen to tell people where his family come from.
It's believed there are plans for Mr Biden to visit Ireland during his four year term.
Last week, the Taoiseach said he invited Mr Biden, and the response he got was "try and keep me out".
The Foreign Affairs Minister says he hopes to welcome Joe Biden to Ireland early in his presidency.
Simon Coveney says the country takes great pride in his inauguration.
He says Mr Biden has always been a friend to Ireland and he looks forward to working with him on strengthening Irish-US relations.
Earlier today, Mr Trump's made his final speech as US President before flying to Florida on Air Force One.
He says it was an 'honour and a privilege' to serve.
And he's paid tribute the family members who were part of his administration.
"People have no idea how hard this family worked, and they worked for you. They could have had an easier job but they did a fantastic job."
Melania Trump also spoke at a departure ceremony in Maryland.
"Being your First Lady was my greatest honor.Thank you for your love and your support. You will be in my thoughts and prayers. God bless you all, god bless your families and god bless this beautiful nation."
The outgoing President did not attend the ceremony.
The President of the European Commission has welcomed Joe Biden's inauguration, saying Europe 'has a friend' in the White House.