How Many Americans Claim Irish Ancestry?

About 11%, or 35 million out of about 310 million, Americans claim Irish ancestry, according to 2011 US Census data. Ireland's total population is about 4.6 million citizens, which means that the US has over 7 times more people of Irish heritage than Ireland. These numbers were split rather evenly between both men and women and across a fairly wide range of age groups and levels of education. The large number of Irish-Americans may be traced back to the country's wave of Irish immigration experienced in the mid 1800s.

More facts about Irish-Americans:

• Although Boston has an Irish-American population of about 20%, Butte, Montana actually has the highest Irish-American population of any metropolitan city with around 24% of citizens claiming Irish ancestry.
• In 1995, the US Congress officially declared March "Irish-American Heritage Month."
• Only German descent was more widely claimed in the 2011 US Census data, with about 47 million Americans claiming German ancestry.