2000
#8,562
National surname rank
Recorded bearers 3,541
First available Census row
Per 100,000 1.31
Rare Last name
Lonergan
An Irish surname derived from Ó Longargáin, meaning "descendant of Longargán," a personal name of uncertain origin.
According to the 2020 US Census Bureau surname tables, roughly 4,062 Americans carry the last name Lonergan. That puts it at #8,875 in the national surname ranking, appearing at a frequency of 1.19 per 100,000 people (about 1 in 84,381 residents).
This page is the full Name Census profile for the Lonergan 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 Lonergan with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
4.1K
1 in 84,381
Census rank
#8,875
2020 decennial data
Per 100,000
1.2
Frequency rate
Recorded bearers
3.5K
rare in the US
Popularity narrative
The Census Bureau recorded 3,542 bearers of the surname Lonergan in its 2020 decennial surname file. At a rate of 1.19 per 100,000 residents, it holds the 8875th position in the national surname ranking.
Among Census respondents with the surname Lonergan, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (2.6%).
Origin
Meaning and origin of Lonergan
The surname Lonergan originated in Ireland and is derived from the Gaelic personal name Lonargán, which means "descendant of Lonargan." The name Lonargan itself is a combination of two Gaelic words: "lon," meaning a blackbird, and "argán," meaning a little hero or champion.
Lonergan is an anglicized version of the Irish Ó Longargáin surname, which means "descendant of Lonargán." The Ó prefix in Irish surnames indicates a patronymic name, denoting "grandson of" or "descendant of." The name was prevalent in counties Tipperary and Kilkenny in the southeastern part of Ireland.
One of the earliest known records of the name Lonergan can be found in the Annals of the Four Masters, a chronicle of medieval Irish history compiled in the early 17th century. The annals mention a Domhnall Ó Longargáin, who was the Chief of Uí Duach, a territory in County Tipperary, in the year 1286.
In the late 16th and early 17th centuries, several individuals with the surname Lonergan are mentioned in the Fiants of the Tudor Sovereigns, a collection of administrative records from the Tudor period in Ireland. These include Edmund Lonergan, who was granted land in County Tipperary in 1606, and Donell Lonergan, who was pardoned for his involvement in the Desmond Rebellions in 1586.
Notable individuals with the surname Lonergan throughout history include:
1. Donal Cam O'Lonergan (c. 1555-1624), an Irish Catholic priest and writer who fled Ireland during the Elizabethan persecution of Catholics.
2. Patrick Lonergan (1834-1903), an Irish-American civil engineer who designed and constructed several major bridges in the United States.
3. Bernard Lonergan (1904-1984), a Canadian Jesuit priest, philosopher, and theologian known for his influential works on philosophical method and theology.
4. Donal Lonergan (1937-2003), an Irish actor best known for his roles in films such as "The Commitments" and "The Boxer."
5. Amanda Lonergan (born 1976), an American actress and producer known for her work in television shows like "Desperate Housewives" and "The O.C."
The surname Lonergan is also associated with several place names in Ireland, such as Lonergan's Cross and Lonergan's Hill in County Tipperary, reflecting the historical presence of the family in that region.
Demographics
Ancestry and ethnicity for Lonergan
Among Census respondents with the surname Lonergan, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (2.6%).
The bar chart below shows how Lonergan 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 Lonergan surname at the time of the 2020 Census, not any inherent property of the name itself.
- White91.7% · 3,248
- Hispanic or Latino3.7% · 131
- Two or more races2.6% · 91
- Black or African American1.2% · 42
- Asian and Pacific Islander0.7% · 25
- American Indian and Alaska Native0.1% · 5
Timeline
Historical Census data for Lonergan
Lonergan 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
#8,817
National surname rank
Recorded bearers 3,713
+172 bearers (+4.9%)
Per 100,000 1.26
Rank movement Down 255 places
2020
#8,875
National surname rank
Recorded bearers 3,542
-171 bearers (-4.6%)
Per 100,000 1.19
Rank movement Down 58 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #8,562 | 3,541 | 1.31 | First available Census row | First available Census row |
| 2010 | #8,817 | 3,713 | 1.26 | +172 bearers (+4.9%) | Down 255 places |
| 2020 | #8,875 | 3,542 | 1.19 | -171 bearers (-4.6%) | Down 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 Lonergan 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 | #8,817 | #8,875 | -0.7% |
| Count | 3,713 | 3,542 | -4.6% |
| Per 100K | 1.26 | 1.19 | -6.0% |
Between the 2010 and 2020 Census, the number of Lonergan bearers went from 3,713 to 3,542 (-4.6% change). The surname moved down 58 positions in the national ranking, going from #8,817 to #8,875.
Notable bearers
Famous people with the surname Lonergan
FAQ
Lonergan surname: questions and answers
How many people in the U.S. have the surname Lonergan?
Name Census estimates that about 4,062 living Americans carry the surname Lonergan. Using the current population baseline, that works out to roughly 1 in 84,381 residents.
How common is Lonergan?
Lonergan ranks #8,875 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 1.19 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 3,542 people with the surname Lonergan. That is different from the site's living-bearer estimate (4,062), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 1.19 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 1.19 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 Lonergan.
Has Lonergan become more or less common over time?
Between 2010 and 2020, the surname Lonergan went from 3,713 recorded bearers to 3,542. That is a decrease of 171 (-4.6%). In the national ranking it fell from #8,817 to #8,875.
What does the Census say about the background of Lonergan?
Among Census respondents with the surname Lonergan, the largest self-reported group is White at 91.7%. The next largest groups are Hispanic (3.7%) and Two or More Races (2.6%). 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 Lonergan in the 2020 Census, accounting for 91.7% (3,248 people in the source table).
What is the full ancestry breakdown?
Lonergan 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 (2.6%). 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 Lonergan (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 Lonergan mean?
An Irish surname derived from Ó Longargáin, meaning "descendant of Longargán," a personal name of uncertain origin. 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 Lonergan (1.19 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 Americans have the surname Lonergan?
For a faster, more casual read, check HowManyOfMe.org — our sister site built around that single question.