2000
#8,495
National surname rank
Recorded bearers 3,573
First available Census row
Per 100,000 1.32
Rare Last name
Kerwin
An Anglicized form of the Irish surname "Kirwan," derived from the Gaelic "Ó Ciardhubháin," meaning "descendant of the black little comb."
According to the 2020 US Census Bureau surname tables, roughly 3,954 Americans carry the last name Kerwin. That puts it at #9,102 in the national surname ranking, appearing at a frequency of 1.15 per 100,000 people (about 1 in 86,685 residents).
This page is the full Name Census profile for the Kerwin 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 Kerwin with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
4.0K
1 in 86,685
Census rank
#9,102
2020 decennial data
Per 100,000
1.2
Frequency rate
Recorded bearers
3.4K
rare in the US
Popularity narrative
The Census Bureau recorded 3,448 bearers of the surname Kerwin in its 2020 decennial surname file. At a rate of 1.15 per 100,000 residents, it holds the 9102nd position in the national surname ranking.
Among Census respondents with the surname Kerwin, the largest self-reported group is White at 89.9%. The next largest groups are Hispanic (4.7%) and Two or More Races (3.1%).
Origin
Meaning and origin of Kerwin
The surname Kerwin originated in Ireland and is believed to have derived from the Irish Gaelic name Ciarán, which means "little dark one" or "descendant of Ciar." The name Ciar was an ancient Irish personal name, and the suffix "-án" was used as a diminutive.
Kerwin is an anglicized version of the Irish surname Ó Ciarán or Ó Ciaráin, which means "descendant of Ciarán." The prefix "Ó" signifies "grandson" or "descendant of" in Irish. The name was initially found in County Mayo, where the Ó Ciaráin sept (clan) was based.
One of the earliest recorded instances of the name Kerwin can be traced back to the 13th century in the Annals of the Four Masters, a chronicle of medieval Irish history. The annals mention several members of the Ó Ciaráin family, including Maolmuire Ó Ciaráin, who was recorded as the Bishop of Annaghdown in County Galway in 1249.
In medieval times, the Kerwin family was prominent in County Mayo, particularly in the area around Ballina and Crossmolina. They held significant landholdings and played a role in local politics and affairs.
During the 16th and 17th centuries, the surname underwent various spelling variations, such as Kerwin, Kerwan, Kerwan, and Kirwin, due to the anglicization of Irish names and the lack of standardized spelling at the time.
Notable individuals with the surname Kerwin throughout history include:
1. Matilda Kerwin (c. 1600s), an Irish woman who was one of the first settlers in the American colony of Maryland in the 17th century.
2. John Kerwin (1765-1848), an Irish-born American merchant and politician who served as Mayor of Baltimore from 1826 to 1828.
3. Joseph P. Kerwin (1932-2019), an American astronaut and physician who was part of the Skylab 2 mission in 1973, spending 28 days in space.
4. William Kerwin (1837-1916), an Irish-born American prelate who served as the Bishop of Fort Wayne from 1893 to 1916.
5. Kathleen Kerwin (born 1957), a Canadian academic and the current President and Vice-Chancellor of the University of British Columbia.
The surname Kerwin continues to be found predominantly in Ireland, particularly in Counties Mayo, Galway, and Sligo, as well as among Irish diaspora communities around the world.
Demographics
Ancestry and ethnicity for Kerwin
Among Census respondents with the surname Kerwin, the largest self-reported group is White at 89.9%. The next largest groups are Hispanic (4.7%) and Two or More Races (3.1%).
The bar chart below shows how Kerwin 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 Kerwin surname at the time of the 2020 Census, not any inherent property of the name itself.
- White89.9% · 3,099
- Hispanic or Latino4.7% · 161
- Two or more races3.1% · 108
- Black or African American1.0% · 36
- Asian and Pacific Islander0.9% · 31
- American Indian and Alaska Native0.4% · 13
Timeline
Historical Census data for Kerwin
Kerwin 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
#8,635
National surname rank
Recorded bearers 3,808
+235 bearers (+6.6%)
Per 100,000 1.29
Rank movement Down 140 places
2020
#9,102
National surname rank
Recorded bearers 3,448
-360 bearers (-9.5%)
Per 100,000 1.15
Rank movement Down 467 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #8,495 | 3,573 | 1.32 | First available Census row | First available Census row |
| 2010 | #8,635 | 3,808 | 1.29 | +235 bearers (+6.6%) | Down 140 places |
| 2020 | #9,102 | 3,448 | 1.15 | -360 bearers (-9.5%) | Down 467 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 Kerwin 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 | #8,635 | #9,102 | -5.4% |
| Count | 3,808 | 3,448 | -9.5% |
| Per 100K | 1.29 | 1.15 | -10.6% |
Between the 2010 and 2020 Census, the number of Kerwin bearers went from 3,808 to 3,448 (-9.5% change). The surname moved down 467 positions in the national ranking, going from #8,635 to #9,102.
FAQ
Kerwin surname: questions and answers
How many people in the U.S. have the surname Kerwin?
Name Census estimates that about 3,954 living Americans carry the surname Kerwin. Using the current population baseline, that works out to roughly 1 in 86,685 residents.
How common is Kerwin?
Kerwin ranks #9,102 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 1.15 per 100,000 residents, which is about 1 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 3,448 people with the surname Kerwin. That is different from the site's living-bearer estimate (3,954), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 1.15 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 1.15 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 1 of them to have the surname Kerwin.
Has Kerwin become more or less common over time?
Between 2010 and 2020, the surname Kerwin went from 3,808 recorded bearers to 3,448. That is a decrease of 360 (-9.5%). In the national ranking it fell from #8,635 to #9,102.
What does the Census say about the background of Kerwin?
Among Census respondents with the surname Kerwin, the largest self-reported group is White at 89.9%. The next largest groups are Hispanic (4.7%) and Two or More Races (3.1%). 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 Kerwin in the 2020 Census, accounting for 89.9% (3,099 people in the source table).
What is the full ancestry breakdown?
Kerwin appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (89.9%), Hispanic (4.7%), Two or More Races (3.1%). 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 Kerwin (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 Kerwin mean?
An Anglicized form of the Irish surname "Kirwan," derived from the Gaelic "Ó Ciardhubháin," meaning "descendant of the black little comb." 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 Kerwin (1.15 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 share the surname Kerwin?
For a faster, more casual read, check HowManyOfMe.org — our sister site built around that single question.