As tens of thousands of people gathered to welcome him during a tour of the county where his ancestors were born, US Vice President Joe Biden paid tribute to his Irish heritage.
When he visited the region his great-great-grandfather had left for America, he claimed it “felts like coming home” in a speech he gave in a pub in County Louth.
After a brief visit to Northern Ireland to commemorate the 25th anniversary of the Good Friday peace deal, he is currently on a three-day visit to the Republic of Ireland.
After stepping off Air Force One on to the rain-soaked runway at Dublin Airport he was met by Taoiseach (Irish Prime Minister) Leo Varadkar.
He then travelled to meet distant relatives in the Cooley Peninsula and the village of Carlingford in County Louth on Ireland’s east coast.
In Carlingford crowds lined the quayside as the presidential motorcade arrived.
Later there were shouts of “welcome home, Joe” when Mr Biden arrived in Dundalk to address an audience, including some of his relatives, at the town’s Windsor Bar.
He said Irish people were the “only people in the world in my view who are actually nostalgic about the future”.
“It is because, more than anything in my experience, hope is what beats in the heart of all people and in particular in the hearts of the Irish,” he added.
“Every action is about hope we can make things better.”
The president also visited a Dundalk shop owned by Jerome McAteer, who said he was honoured to sell Mr Biden some sweet treats, including lemon meringue and chocolate eclairs.
“He was talking a lot about his Irish background,” said Mr McAteer.
He runs the shop with his partner Bobby Wain, who said it had been an unforgettable day for them and their staff.
“Mindblowing – one of those days you’ll never forget,” he said.
Earlier Mr Biden completed a brief-but-landmark visit to Belfast, where he called for politicians to restore the power-sharing government at Stormont, which collapsed over a year ago.
He used a speech at Ulster University to praise the “tremendous progress” since the Good Friday Agreement was signed in 1998.
The peace deal largely brought to an end more than 30 years of violent conflict known as the Troubles.
“This place is transformed by peace; made technicolour by peace; made whole by peace,” he said.
President Biden regularly speaks of his Irish heritage and had promised to visit the country during his term in office.
A US genealogist who researched Mr Biden’s lineage has estimated he is “roughly five-eighths” Irish.
His maternal great-great-grandfather Owen Finnegan departed Carlingford in County Louth in the late 1840s to travel to America.
Among his great-grandparents was Edward Blewitt, who left the west coast town of Ballina in County Mayo in 1850 to emigrate to the US.
He settled in Scranton in Pennsylvania as the devastating Irish potato famine was causing widespread starvation.
In his speech in Dundalk, Mr Biden said his ancestors left Ireland at about the same time as former US President Barack Obama’s great-great-great-grandfather Falmouth Kearney, who was from Moneygall in County Offaly.
“They would never have dreamed that their grandsons would have been presidents of the United States,” he said.
Mr Biden was given a tour of Carlingford Castle alongside the Tánaiste (Irish Deputy Prime Minister) Micheál Martin.
Asked about his feelings on the visit, the president replied: “It’s wonderful. It feels like I’m coming home.”
Commenting on the wet weather, he added: “It’s fine – it’s Ireland.”
The US president greeted a crowd of about 5,000 people as he visited Dundalk, a town a few miles from the Irish border.
Mr Biden also made a visit to a cafe where he met staff before addressing an audience at the pub.
“When you’re here you wonder why anybody would want to leave,” he told them.
In the coming days, President Biden is expected to speak to politicians at the Oireachtas (Irish parliament) and meet more relatives in Ballina.