2000
#8,360
National surname rank
Recorded bearers 3,639
First available Census row
Per 100,000 1.35
Rare Last name
Mcsweeney
Derived from the Gaelic "Mac Suibhne," meaning "son of Suibhne," a personal name meaning "pleasant" or "well-disposed."
According to the 2020 US Census Bureau surname tables, roughly 4,219 Americans carry the last name Mcsweeney. That puts it at #8,581 in the national surname ranking, appearing at a frequency of 1.23 per 100,000 people (about 1 in 81,241 residents).
This page is the full Name Census profile for the Mcsweeney 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 Mcsweeney with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
4.2K
1 in 81,241
Census rank
#8,581
2020 decennial data
Per 100,000
1.2
Frequency rate
Recorded bearers
3.7K
rare in the US
Popularity narrative
The Census Bureau recorded 3,679 bearers of the surname Mcsweeney in its 2020 decennial surname file. At a rate of 1.23 per 100,000 residents, it holds the 8581st position in the national surname ranking.
Among Census respondents with the surname Mcsweeney, the largest self-reported group is White at 90.2%. The next largest groups are Hispanic (4.4%) and Two or More Races (2.8%).
Origin
Meaning and origin of Mcsweeney
The surname McSweeney originated in Ireland, specifically in the southwestern region of County Cork. It is derived from the Irish Gaelic name Mac Suibhne, which means "son of Suibhne." Suibhne is an ancient personal name that has been anglicized as Sweeney.
The McSweeney name can be traced back to the 11th century when the family was part of the Dál gCais clan, which ruled the region of Thomond (now County Clare and parts of County Limerick). The McSweeneys were a prominent sept (branch) of the Dál gCais and held significant power and influence in the area.
In the 14th century, a notable figure named Niall McSweeney was recorded as the Chief of the McSweeneys in County Cork. He was involved in various conflicts and battles during the Norman invasion of Ireland.
The name McSweeney is also mentioned in the Annals of the Four Masters, an important chronicle of medieval Irish history compiled in the 17th century. The annals record several McSweeney clan chiefs and their activities during that period.
One of the earliest recorded instances of the surname is found in the Papal Taxation Rolls of 1302-1307, which list a "John McSweeney" as a tenant in County Cork.
In the 16th century, a famous McSweeney was Donogh McSweeney, who became the Bishop of Raphoe in County Donegal. He was a prominent figure in the Irish Catholic Church during the tumultuous years of the Protestant Reformation.
Another notable McSweeney was John McSweeney (1754-1826), an Irish-born political activist and military leader who fought in the American Revolutionary War. He later became a prominent figure in the Irish Patriot movement, advocating for Irish independence.
In the 19th century, John McSweeney (1834-1906) was an Irish-American journalist and politician who served as the 49th Mayor of New York City from 1894 to 1897.
The McSweeney name has also been associated with various place names in Ireland, such as Ballymacswiney (meaning "McSweeney's town") in County Cork and Kilmeedy (derived from Cill Mhic Suibhne, meaning "McSweeney's church") in County Limerick.
Over time, the name has been anglicized and has variations such as Sweeney, Sweeny, and Swiney, but McSweeney remains the most common spelling.
Demographics
Ancestry and ethnicity for Mcsweeney
Among Census respondents with the surname Mcsweeney, the largest self-reported group is White at 90.2%. The next largest groups are Hispanic (4.4%) and Two or More Races (2.8%).
The bar chart below shows how Mcsweeney 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 Mcsweeney surname at the time of the 2020 Census, not any inherent property of the name itself.
- White90.2% · 3,320
- Hispanic or Latino4.4% · 163
- Two or more races2.8% · 104
- Black or African American1.7% · 62
- Asian and Pacific Islander0.7% · 24
- American Indian and Alaska Native0.2% · 6
Timeline
Historical Census data for Mcsweeney
Mcsweeney 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
#8,639
National surname rank
Recorded bearers 3,807
+168 bearers (+4.6%)
Per 100,000 1.29
Rank movement Down 279 places
2020
#8,581
National surname rank
Recorded bearers 3,679
-128 bearers (-3.4%)
Per 100,000 1.23
Rank movement Up 58 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #8,360 | 3,639 | 1.35 | First available Census row | First available Census row |
| 2010 | #8,639 | 3,807 | 1.29 | +168 bearers (+4.6%) | Down 279 places |
| 2020 | #8,581 | 3,679 | 1.23 | -128 bearers (-3.4%) | Up 58 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 Mcsweeney 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 | #8,639 | #8,581 | 0.7% |
| Count | 3,807 | 3,679 | -3.4% |
| Per 100K | 1.29 | 1.23 | -4.6% |
Between the 2010 and 2020 Census, the number of Mcsweeney bearers went from 3,807 to 3,679 (-3.4% change). The surname moved up 58 positions in the national ranking, going from #8,639 to #8,581.
FAQ
Mcsweeney surname: questions and answers
How many people in the U.S. have the surname Mcsweeney?
Name Census estimates that about 4,219 living Americans carry the surname Mcsweeney. Using the current population baseline, that works out to roughly 1 in 81,241 residents.
How common is Mcsweeney?
Mcsweeney ranks #8,581 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 1.23 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 3,679 people with the surname Mcsweeney. That is different from the site's living-bearer estimate (4,219), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 1.23 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 1.23 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 Mcsweeney.
Has Mcsweeney become more or less common over time?
Between 2010 and 2020, the surname Mcsweeney went from 3,807 recorded bearers to 3,679. That is a decrease of 128 (-3.4%). In the national ranking it rose from #8,639 to #8,581.
What does the Census say about the background of Mcsweeney?
Among Census respondents with the surname Mcsweeney, the largest self-reported group is White at 90.2%. The next largest groups are Hispanic (4.4%) and Two or More Races (2.8%). 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 Mcsweeney in the 2020 Census, accounting for 90.2% (3,320 people in the source table).
What is the full ancestry breakdown?
Mcsweeney appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (90.2%), Hispanic (4.4%), Two or More Races (2.8%). 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 Mcsweeney (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 Mcsweeney mean?
Derived from the Gaelic "Mac Suibhne," meaning "son of Suibhne," a personal name meaning "pleasant" or "well-disposed." 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 Mcsweeney (1.23 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 surname Mcsweeney?
For a quick modern estimate, our sister site HowManyOfMe.org answers that in one glance, with the living-bearer count front and centre.