The contribution of Ireland to the United States in this, the 250th anniversary year of the US Declaration of Independence, was marked by wreath laying ceremonies in Washington, DC, at the grave of John F Kennedy.
Three other former presidents were also honoured, including in New York, with a lecture and specially commissioned poem.
The events were organised by Irish America 250, an organisation set up to highlight the Irish contribution to America's story.
At Arlington National Cemetery in the nation’s capital, the Irish America 250 Committee and the Ancient Order of Hibernians gathered to lay a wreath on the grave of John F Kennedy.
Sean Pender the National President of the Ancient Order of Hibernians - an Irish-American Catholic organisation that is almost 190 years old, said: "We are doing this to remember our past and to remember the contributions in this very special year of 250 years of America.
"The idea was that we would take a look at all the contributions of all the Irish to the presidency. Amazing number of 23 have come from the island of Ireland. And of course, in a very special way, John Kennedy, being the first Irish Catholic and indeed a member of the Ancient Order of Hibernians, it was fitting we come back here and honour him as all that is great about what Ireland has brought to this country."
President's Day is a federal holiday to mark the birthday of George Washington, the first of the 47 presidents. But a surprisingly high number of that select group have Irish connections.
Professor Darragh Gannon, the assistant director of Irish Studies at Georgetown University and lead Historian for Irish America 250 said: "In fact, there are 23 presidents who can claim Irish heritage here in the United States all the way back to Andrew Jackson and going right up to the present to President Joe Biden.
"And that's a remarkable story, not just of American history, but of Irish American history. It tells us that the Irish story of emigration from the famine and before was not a story just of exile.
"It was a story of success and of political achievement across the Atlantic. So Irish history is no longer an island story. It's a transatlantic story."
The chairman and CEO of Irish America 250, Kevin Sullivan, said the event in New York later tonight will include a lecture by Niall O’Dowd, the publisher of the Irish Voice newspaper, on his book Washington and the Irish; and leading Irish poet Micheal O'Siadhail will give a first reading of a new poem, IRISH AMERICA, commissioned to mark the America 250 celebration.
Prof Gannon said: "This is a national year of commemoration, Irish America 250 is leading the charge, working very closely with the Department of Foreign Affairs in Dublin, the Northern Ireland executive in Belfast, and with stakeholders here in America. So, we would encourage anyone in Ireland who's interested in promoting Irish heritage on both sides of the Atlantic to reach out to us and be part of a historic year."
For National President of the Ladies Ancient Order of Hibernians, Mary Ann Lubinsky, today’s wreath laying in Arlington Cemetery was most of all about honouring JFK: "It was truly an honour for me to be there and to place the wreath on his grave today. I've got the goosebumps again. It was magnificent!"
The main national celebration takes place on the fourth of July. Events throughout the year have been organised by the America 250 Committee of politicians, with honorary co-chairs George and Laura Bush and Barack and Michelle Obama.
