John Cunningham, owner of Claddagh Rings, has crated a visual showing the US Presidents who had at least some Irish ancestry. 22 American presidents claim Irish roots which is half of all the 44 presidents up to and including Barack Obama.
You can see the visual at by clicking here.
Depending upon which web browser you use in your computer, you might see it full-sized or it may display as a miniature image. If it is miniature, most web browsers can display it larger by simultaneously pressing CONTROL and the Plus Key several times. Macintosh users will need to press COMMAND and the Plus Key several times.