Of the 44 men who have become president of the United States, 22 can trace some of their ancestry to Ireland. Irish heritage is strong in the country and is among the top three ancestries in more than half of U.S. states, according to the Census.

About 33 million Americans are of Irish descent. 24/7 Tempo has compiled a list of those with Irish ancestry who have served as president.

Starting with Andrew Jackson, who became president in 1829, most of the country’s chief executives with Irish lineage came from Ireland’s northern counties of Tyrone and Antrim. All were Protestant and identified as Scots-Irish to distinguish themselves from the Catholics living in the southern part of the island.

It wasn’t until John F. Kennedy — the most Irish of all the American chief executives — became the first Catholic elected as president in 1960 that any president of Irish extraction made his ethnicity a point of pride. Kennedy’s visit to Ireland in June of 1963 prompted an enthusiastic reaction and he vowed to return to his ancestral home. That never happened. He was assassinated five months later at age 46, one of the youngest presidents to die in office. These are the 37 most famous assassinations in American history.

Since Kennedy’s election, other presidents have used their Irish connections to mine the votes of Irish Americans. Some presidents with Irish ancestry have journeyed to the Emerald Isle while in office, among them Richard Nixon (1970), Ronald Reagan (1984), and Barack Obama (2011). Even though Bill Clinton’s Irish connection has not been fully verified, the 42nd president was a staunch proponent of the peace process in Northern Ireland. He visited the island three times as president.

24/7 Tempo compiled its list of U.S. presidents with Irish heritage by reviewing websites such as ulsterscotsagency.com, academica.edu, irishcentral.com, bbc.com, and whitehouse.gov. As many as 25 presidents supposedly claim Irish ancestry. However, three of them — William Henry Harrison, Abraham Lincoln, and Bill Clinton — do not have fully corroborated evidence of Irish heritage. Our list is composed of presidents with the most verifiable claims to Irish ancestry.

Click here to see the U.S. presidents with Irish heritage.