resident Joe Biden declared that the US and Ireland are “united by history, heritage and hope” as he ended his visit to the island.
Mr Biden made a passionate public speech in Ballina, Co Mayo, on Friday evening in front of a crowd of thousands.
The president said his trip to the town “feels like coming home” and told spectators millions of Americans claim to have Irish heritage, adding: “More would if they could.”
Emphasising his link to the area, he said: “Over the years stories of this place have become part of my soul, part of my family lore.”
Taoiseach Leo Varadkar hailed the success of the visit, stating there was no doubt Ireland had an ally in the White House.
The trip ended when Mr Biden left Ireland West Airport to fly onto Dublin, from where he will then immediately set off for his home state of Delaware.
Earlier in the day, the president became emotional during a visit to Knock shrine following a chance meeting with priest Fr Frank O’Grady, who gave the last rites to his son Beau Biden before he died of brain cancer in 2015.
His emotion-filled final day also saw Mr Biden visit the Mayo Roscommon Hospice, where there is a plaque in memory of his late son.
Telling the crowd about his visit to the centre, the president said: “I can tell you how special it is that a piece of his legacy lives here among his ancestors.
“Thinking about it I could hear my dad’s voice again. He’d always say ‘Joe, remember family is the beginning, the middle and the end’.
“The beginning, middle and end, that’s the Irish of it.”
Mr Biden spoke throughout his 20-minute speech of his fondness for Ireland and the US’s relationship.
“Everything between Ireland and America runs deep,” he said.
“Our history, our heritage, our sorrows, our future, our friendship. But more than anything, hope is what beats in the hearts of all our people.
“For centuries during times of darkness and despair, hope has kept us marching forward toward a better future, one of greater liberty, greater dignity and greater possibilities.”
The president’s son Hunter Biden and sister Valerie Biden Owens sat in the front row of the VIP section to the side of the stage for the speech.
Mr Biden’s tour of Ireland saw him return to his ancestral roots, with visits to both Co Louth and Co Mayo.
Before his speech, the president received a physical piece of his family’s past at a heritage centre in the form of a 200-year-old brick recovered from the site of his family’s ancestral home in Ballina.
He spent more than an hour at the North Mayo Heritage and Genealogical Centre learning about his Irish roots, and during his trip to the hospice he met with distant cousin Laurita Blewitt.
On Friday evening, he told the crowds of his ancestor Edward Blewitt, who he said worked in the old Ballina brickyard.
The president said during one of his engagements in Co Mayo, he saw a record from 1828 that said Mr Blewitt was paid 21 pounds and 12 shillings to help supply 27,000 bricks for St Muredach’s Cathedral, which was nearby as he addressed the crowd.
“As he laboured, I’m sure he would imagine that one day his family would worship here, that his children would be baptised here like his son Patrick was, and that future generations of his family would mark the milestones of their lives here in the sturdy walls,” he said.
“But I doubt he ever imagined his great-great-great grandson would return 200 years later as president of the United States of America.”
Mr Biden said he and his siblings were raised with “a fierce pride in our Irish ancestry”.
“A pride that spoke to both the history that binds us but more importantly the values that unite us,” he said.
“To this day I can still remember hearing my dad say at the dinner table, ‘Joey, everyone is entitled to be treated with dignity and respect’, I can still hear my mom tell me, ‘Joey, nobody is better than you but everybody is your equal’.”
The president also spoke of the Good Friday Agreement, calling it “25 years of peace and progress”.
“It is a reminder the importance of peace and what you can accomplish when we work together in common cause,” Mr Biden said.