2000
#33,292
National surname rank
Recorded bearers 647
First available Census row
Per 100,000 0.24
Very Rare Last name
Moynahan
An Anglicized form of the Irish surname Ó Muimhneacháin meaning "descendant of Muimhneachán".
According to the 2020 US Census Bureau surname tables, roughly 722 Americans carry the last name Moynahan. That puts it at #37,907 in the national surname ranking, appearing at a frequency of 0.21 per 100,000 people (about 1 in 474,729 residents).
This page is the full Name Census profile for the Moynahan 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.
Bearers in the US
722
1 in 474,729
Census rank
#37,907
2020 decennial data
Per 100,000
0.2
Frequency rate
Recorded bearers
630
very rare in the US
Popularity narrative
The Census Bureau recorded 630 bearers of the surname Moynahan in its 2020 decennial surname file. At a rate of 0.21 per 100,000 residents, it holds the 37907th position in the national surname ranking.
Among Census respondents with the surname Moynahan, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (3.7%).
Origin
Meaning and origin of Moynahan
The surname Moynahan is of Irish origin, and it is derived from the Gaelic word "Maonghamhain," which means "descendant of Maonghamhain." The name Maonghamhain itself is a combination of two Gaelic words: "maon," meaning "wealthy," and "ghamhain," meaning "calf."
The earliest recorded use of the name Moynahan dates back to the 16th century in County Tipperary, Ireland. In 1601, the Moynahan name appeared in the "Fiants of County Tipperary," which were records of grants of land made by the Crown in Ireland.
During the 17th and 18th centuries, the Moynahan family was prominent in County Tipperary, particularly in the areas of Cashel and Fethard. Some notable individuals with the Moynahan surname from this period include John Moynahan (1640-1718), a member of the Irish Parliament, and William Moynahan (1705-1779), a landowner and businessman.
In the 19th century, the Moynahan name spread to other parts of Ireland and beyond. One notable individual from this period was Michael Moynahan (1835-1902), an Irish-American politician who served as the Mayor of Syracuse, New York, from 1892 to 1894.
Other notable individuals with the Moynahan surname include:
1. James Moynahan (1868-1943), an Irish-American Catholic priest and educator in New York City.
2. Brendan Moynahan (1891-1971), an Irish politician and member of the Dáil Éireann (Irish Parliament) from 1927 to 1937.
3. Patrick Moynahan (1918-1987), an Irish hurler who played for the Tipperary senior hurling team.
4. Brian Moynahan (born 1941), a British author and journalist who has written extensively on military history and international affairs.
5. Bridget Moynahan (born 1971), an American actress and model, best known for her roles in films such as "Coyote Ugly" and "The Recruit."
The Moynahan surname has also been associated with various place names in Ireland, such as Moynahancourt and Moynahan's Bridge, both located in County Tipperary.
Demographics
Ancestry and ethnicity for Moynahan
Among Census respondents with the surname Moynahan, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (3.7%).
The bar chart below shows how Moynahan 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 Moynahan surname at the time of the 2020 Census, not any inherent property of the name itself.
- White91.7% · 578
- Hispanic or Latino3.7% · 23
- Two or more races3.7% · 23
- Black or African American0.5% · 3
- Asian and Pacific Islander0.3% · 2
- American Indian and Alaska Native0.2% · 1
Timeline
Historical Census data for Moynahan
Moynahan 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
#35,489
National surname rank
Recorded bearers 634
-13 bearers (-2.0%)
Per 100,000 0.21
Rank movement Down 2,197 places
2020
#37,907
National surname rank
Recorded bearers 630
-4 bearers (-0.6%)
Per 100,000 0.21
Rank movement Down 2,418 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #33,292 | 647 | 0.24 | First available Census row | First available Census row |
| 2010 | #35,489 | 634 | 0.21 | -13 bearers (-2.0%) | Down 2,197 places |
| 2020 | #37,907 | 630 | 0.21 | -4 bearers (-0.6%) | Down 2,418 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 Moynahan 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 | #35,489 | #37,907 | -6.8% |
| Count | 634 | 630 | -0.6% |
| Per 100K | 0.21 | 0.21 | 0.4% |
Between the 2010 and 2020 Census, the number of Moynahan bearers went from 634 to 630 (-0.6% change). The surname moved down 2,418 positions in the national ranking, going from #35,489 to #37,907.
Notable bearers
Famous people with the surname Moynahan
FAQ
Moynahan surname: questions and answers
How many people in the U.S. have the surname Moynahan?
Name Census estimates that about 722 living Americans carry the surname Moynahan. Using the current population baseline, that works out to roughly 1 in 474,729 residents.
How common is Moynahan?
Moynahan ranks #37,907 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.21 per 100,000 residents, which is about 0 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 630 people with the surname Moynahan. That is different from the site's living-bearer estimate (722), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.21 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.21 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 0 of them to have the surname Moynahan.
Has Moynahan become more or less common over time?
Between 2010 and 2020, the surname Moynahan went from 634 recorded bearers to 630. That is a decrease of 4 (-0.6%). In the national ranking it fell from #35,489 to #37,907.
What does the Census say about the background of Moynahan?
Among Census respondents with the surname Moynahan, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (3.7%). 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 Moynahan in the 2020 Census, accounting for 91.7% (578 people in the source table).
What is the full ancestry breakdown?
Moynahan appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (91.7%), Hispanic (3.7%), Two or More Races (3.7%). 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 Moynahan (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 Moynahan mean?
An Anglicized form of the Irish surname Ó Muimhneacháin meaning "descendant of Muimhneachán". 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 Moynahan (0.21 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 are called Moynahan?
See how many people are called Moynahan on HowManyOfMe.org, our sister site built around that single question.