As President Obama prepares to visit his ancestral family home, Moneygall, County Offaly, historians are taking a look at the 22 American presidents with their roots in Ireland.
John Robert Greene, a historian and author of dozens of books, explained "It's very simple, Catholic votes…There's not a huge love of Irish tradition, with the possible exception of JFK and Ronald Reagan, not a huge love of Irish culture, with the possible exception of JFK, Reagan and Bill Clinton, but there's a huge love for Catholic votes and particularly Irish Catholic votes.
"That's why there is a pilgrimage every four years and that's why Obama is going."
Referring to the 1952 classic John Wayne movie Greene said "I doubt he really wants to be photographed in a cottage like The Quiet Man, but he will."
Obama will visit Moneygall, County Offaly, where his great-great-great-great grandfather was a shoe maker. In 1850 Falmouth Kearney, son of a shoemaker Joseph, left for the US. Now the village with a population of 300 is gearing up for the May 23 visit.
In 1984 President Ronald Regan and his wife Nancy visited Ballyporeen, in County Tipperary. Eight bed and breakfasts, two cafes and souvenir businesses opened up. The tourist boom lasted for six or seven years.
The local pub was renamed after the president before he even arrived and after his death in 2005 the Reagan presidential library acquired the interior of the pub. The walls were decked with images of the president around the world.
The pub's owner, Mary O'Farrell, told the BBC, "He was real Irish in temperament…You'd know he was Irish, he had that sense of humor and glint in his eye."
Greene told the BBC that Obama's trip to Ireland, albeit one night, will play beautifully in cities like Buffalo, Cleveland, Detroit and in parts of New York City and Massachusetts. He said news of Obama's visit will surely make it into Catholic newspapers, which might not otherwise follow Obama due to his stance on abortion and other issues.
Most of the 22 Irish American presidents have their roots in Tyrone and Antrim and come from a Protestant background of 19th century Ulster. They generally settled in the south and west in the US. Later they labeled themselves Scots-Irish in a bid to distinguish themselves from the Catholics fleeing Ireland during the potato famine in 1840s. It served those running for presidency better not to associate with those coming out of Ireland, who were being accused of stealing American jobs.
During the early 20th Century these attitudes began to change and then along came John F Kennedy.
Although neither his parents nor grandparents were born in Ireland he forged an solid Irish identity and he became the first Catholic to take the office. At Kennedy's rallies, filled with prominent Irish Catholics, such as Tip O'Neill, "Danny Boy" was the tune of choice.
Talking about Kennedy, the historian, Greene said "He clearly wanted the link to the Irish and he made himself more Irish than any other American president."
Since Kennedy (who was assassinated on November 22, 1963) every president apartment from Gerald Ford has claimed some sort of Irish ancestry, says Greene. Although he commented that in Bill Clinton's case there was no evidence.
Carl Shanahan, founder of Wild Geese, an organization that promotes Irish culture in the US and worldwide, said that what these presidents are doing just exactly what millions of Americans do every day.
Shanahan said "Being Irish doesn't hurt you at any level of society. We were never at war with Americans like the Germans, the Italians and the Japanese. In Washington's army the numbers were a third Irish or Scottish-Irish…There is an affinity by association. It's the reputation of the Irish, the fighting Irish. A guy who gets off his feet and fights the battle and wins. We had boxing champs and baseball teams."