2000
#3,144
National surname rank
Recorded bearers 10,515
First available Census row
Per 100,000 3.90
Uncommon Last name
Leahy
Anglicized form of the Irish surname Ó Laochdha, meaning "descendant of Laochdha," a personal name meaning "heroic" or "warlike."
According to the 2020 US Census Bureau surname tables, roughly 12,241 Americans carry the last name Leahy. That puts it at #3,306 in the national surname ranking, appearing at a frequency of 3.57 per 100,000 people (about 1 in 28,001 residents).
This page is the full Name Census profile for the Leahy surname. You will find the Census Bureau frequency data, a multi-census history view, an ancestry and ethnicity breakdown based on self-reported demographics, the name's meaning and origin where available, and answers to the most common questions people ask about this surname.
For British records, Name Census UK has a British surname profile for Leahy with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
12K
1 in 28,001
Census rank
#3,306
2020 decennial data
Per 100,000
3.6
Frequency rate
Recorded bearers
11K
uncommon in the US
Popularity narrative
The Census Bureau recorded 10,675 bearers of the surname Leahy in its 2020 decennial surname file. At a rate of 3.57 per 100,000 residents, it holds the 3306th position in the national surname ranking.
Among Census respondents with the surname Leahy, the largest self-reported group is White at 92.3%. The next largest groups are Hispanic (3.6%) and Two or More Races (2.5%).
Origin
Meaning and origin of Leahy
The surname Leahy originated in Ireland and is derived from the Irish Gaelic name "O'Liathain," which means "descendant of the grey-haired one." It is an anglicized version of the Irish name and is found primarily in the counties of Cork, Kerry, and Tipperary.
The earliest recorded instances of the name Leahy can be traced back to the 13th century in various Irish annals and manuscripts. One of the earliest known bearers of the name was Donnchadh O'Liathain, who was mentioned in the Annals of Inisfallen in 1292.
In the 16th century, the name appeared in the Fiants of the Tudor Sovereigns of Ireland, which were records of official acts and appointments. One notable figure from this period was Sir Piers Leahy, who was granted land in County Cork in 1588.
During the 17th century, the name was anglicized to its current spelling, and several Leahys were listed in the 1659 Census of Ireland. This census was conducted by the English government to assess the population and land ownership in Ireland after the Cromwellian conquest.
In the 18th century, the Leahy family played a significant role in the Irish Rebellion of 1798. Patrick Leahy, a prominent leader in the rebellion, was born in 1766 and was later executed for his involvement in the uprising.
Another notable figure from this era was James Leahy (1755-1825), an Irish-born soldier who served in the British Army during the American Revolutionary War and later became a member of the United States Congress.
In the 19th century, several Leahys made their mark in various fields. John Leahy (1795-1868) was an Irish Catholic priest and author, while Michael Leahy (1831-1899) was an Irish-born sculptor who worked in England and received several commissions from Queen Victoria.
One of the most famous Leahys in modern times was William Daniel Leahy (1875-1959), an American naval officer who served as the Chief of Naval Operations during World War II and later as the first chairman of the Joint Chiefs of Staff.
Demographics
Ancestry and ethnicity for Leahy
Among Census respondents with the surname Leahy, the largest self-reported group is White at 92.3%. The next largest groups are Hispanic (3.6%) and Two or More Races (2.5%).
The bar chart below shows how Leahy bearers described their own race and ethnicity on the 2020 Census form. The Census Bureau groups responses into six broad categories: White, Black or African American, Hispanic or Latino, Asian and Pacific Islander, American Indian and Alaska Native, and Two or More Races. When a category has too few respondents for a given surname, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown for every Census year so the breakdown stays comparable over time. When the source file also includes raw headcounts, Name Census shows those alongside the percentages in the legend.
Keep in mind that these are self-reported numbers. A person's surname does not determine their race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the Leahy surname at the time of the 2020 Census, not any inherent property of the name itself.
- White92.3% · 9,855
- Hispanic or Latino3.6% · 388
- Two or more races2.5% · 271
- Asian and Pacific Islander1.0% · 103
- Black or African American0.4% · 43
- American Indian and Alaska Native0.1% · 15
Timeline
Historical Census data for Leahy
Leahy appears in 3 published Census surname files: 2000, 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2010
#3,280
National surname rank
Recorded bearers 11,014
+499 bearers (+4.7%)
Per 100,000 3.73
Rank movement Down 136 places
2020
#3,306
National surname rank
Recorded bearers 10,675
-339 bearers (-3.1%)
Per 100,000 3.57
Rank movement Down 26 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #3,144 | 10,515 | 3.90 | First available Census row | First available Census row |
| 2010 | #3,280 | 11,014 | 3.73 | +499 bearers (+4.7%) | Down 136 places |
| 2020 | #3,306 | 10,675 | 3.57 | -339 bearers (-3.1%) | Down 26 places |
For 2020, the Census Bureau published race and Hispanic-origin columns as counts rather than percentages. Name Census converts those counts back into shares so the ancestry section stays comparable with the older surname files.
Year on year
2010 vs 2020 Census
How has the Leahy surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
20102020
| Metric | 2010 | 2020 | Change |
|---|---|---|---|
| Rank | #3,280 | #3,306 | -0.8% |
| Count | 11,014 | 10,675 | -3.1% |
| Per 100K | 3.73 | 3.57 | -4.3% |
Between the 2010 and 2020 Census, the number of Leahy bearers went from 11,014 to 10,675 (-3.1% change). The surname moved down 26 positions in the national ranking, going from #3,280 to #3,306.
Notable bearers
Famous people with the surname Leahy
FAQ
Leahy surname: questions and answers
How many people in the U.S. have the surname Leahy?
Name Census estimates that about 12,241 living Americans carry the surname Leahy. Using the current population baseline, that works out to roughly 1 in 28,001 residents.
How common is Leahy?
Leahy ranks #3,306 in the 2020 Census surname tables and is classified on this site as "Uncommon." The Census recorded the name at a frequency of 3.57 per 100,000 residents, which is about 4 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 10,675 people with the surname Leahy. That is different from the site's living-bearer estimate (12,241), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 3.57 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 3.57 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 4 of them to have the surname Leahy.
Has Leahy become more or less common over time?
Between 2010 and 2020, the surname Leahy went from 11,014 recorded bearers to 10,675. That is a decrease of 339 (-3.1%). In the national ranking it fell from #3,280 to #3,306.
What does the Census say about the background of Leahy?
Among Census respondents with the surname Leahy, the largest self-reported group is White at 92.3%. The next largest groups are Hispanic (3.6%) and Two or More Races (2.5%). These figures come from the 2020 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Which group reports this surname most often?
White is the largest self-reported group for the surname Leahy in the 2020 Census, accounting for 92.3% (9,855 people in the source table).
What is the full ancestry breakdown?
Leahy appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (92.3%), Hispanic (3.6%), Two or More Races (2.5%). For 2020, the source file also published raw headcounts for each group, which is why this page can show both percentages and counts in the ancestry section.
Is this page using the latest Census data?
Yes. This page is using the latest surname file currently loaded on Name Census, which is 2020. The historical section above also keeps any older Census surname entries we have for Leahy (2000, 2010, 2020).
Does the Census include every surname?
No. The Census Bureau only publishes surnames that appeared at least 100 times in a given decennial Census. That means very rare surnames are excluded entirely, and a surname can appear in one Census release but disappear from a later one if it falls below the reporting threshold.
Why don't the ancestry percentages always add up to exactly 100%?
There are two main reasons: rounding and suppression. The Census Bureau rounds published values, and it may suppress very small cells to protect privacy. For 2020, the Bureau also published raw group counts rather than direct percentages, so Name Census converts those counts back into shares for comparability across census years.
What does Leahy mean?
Anglicized form of the Irish surname Ó Laochdha, meaning "descendant of Laochdha," a personal name meaning "heroic" or "warlike." The fuller origin note on this page goes into more detail.
Where does the surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These files list every surname that appeared 100 or more times in the 2020 Census, along with a count, a per-100,000 rate, and a self-reported demographic breakdown. You can read the full explanation on our methodology page.
How does Name Census estimate living bearers?
For surnames, Name Census does not age cohorts the way it does for first names. Instead, it takes the Census Bureau's published frequency for Leahy (3.57 per 100,000) and applies that rate to the current U.S. resident population to estimate how many living Americans have the surname today.
How many people have the last name Leahy?
Want to know how many people have the surname Leahy? HowManyOfMe.org, our sister site, puts the living-bearer count front and centre.