2000
#780
National surname rank
Recorded bearers 40,310
First available Census row
Per 100,000 14.94
Uncommon Last name
Reilly
Descended from the Irish surname Ó Raghallaigh, meaning "descendant of Raghallach," a personal name meaning "courageous" or "valiant."
According to the 2020 US Census Bureau surname tables, roughly 45,462 Americans carry the last name Reilly. That puts it at #853 in the national surname ranking, appearing at a frequency of 13.26 per 100,000 people (about 1 in 7,539 residents).
This page is the full Name Census profile for the Reilly 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 Reilly with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
45K
1 in 7,539
Census rank
#853
2020 decennial data
Per 100,000
13.3
Frequency rate
Recorded bearers
40K
uncommon in the US
Popularity narrative
The Census Bureau recorded 39,645 bearers of the surname Reilly in its 2020 decennial surname file. At a rate of 13.26 per 100,000 residents, it holds the 853rd position in the national surname ranking.
Among Census respondents with the surname Reilly, the largest self-reported group is White at 92.5%. The next largest groups are Hispanic (3.5%) and Two or More Races (2.4%).
Origin
Meaning and origin of Reilly
The surname Reilly originates from Ireland and is an anglicized version of the Gaelic name O'Raghailligh. It is believed to have derived from the Irish word riaghail, meaning "rule" or "regulator," suggesting that the name may have been initially bestowed upon a local official or magistrate.
In its early form, the name was often spelled as O'Reilly or O'Reyly. It is found in several ancient Irish manuscripts, such as the Annals of the Four Masters, which record notable individuals bearing the name as early as the 12th century.
One of the earliest recorded instances of the name Reilly can be found in the 14th-century Red Book of Ormond, which mentions a Richard Reilly as a witness to a land transaction in County Cavan, Ireland.
The Reilly family was particularly prominent in County Cavan, where they held significant lands and power. The name is also associated with several place names in the region, such as Killyreilly and Ballyreilly.
Notable individuals with the surname Reilly include:
1. Edmund Reilly (c. 1598-1669), a Roman Catholic Archbishop of Armagh who played a crucial role in the Irish Confederate Wars.
2. Andrew Reilly (1742-1809), an Irish-American merchant and politician who served as a delegate to the Continental Congress.
3. Winona Ryder (born Winona Laura Horowitz in 1971), an American actress whose stage name is derived from her father's surname, Reilly.
4. Philip Reilly (1788-1858), an Irish sculptor known for his works in Dublin, including the statue of Daniel O'Connell in the city center.
5. John Reilly (1786-1854), an Irish-American businessman and politician who served as the 16th Mayor of Philadelphia.
The surname Reilly has maintained a strong presence in Ireland, particularly in the counties of Cavan, Longford, and Westmeath, where it can trace its roots back to the medieval period.
Demographics
Ancestry and ethnicity for Reilly
Among Census respondents with the surname Reilly, the largest self-reported group is White at 92.5%. The next largest groups are Hispanic (3.5%) and Two or More Races (2.4%).
The bar chart below shows how Reilly 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 Reilly surname at the time of the 2020 Census, not any inherent property of the name itself.
- White92.5% · 36,666
- Hispanic or Latino3.5% · 1,371
- Two or more races2.4% · 967
- Asian and Pacific Islander0.9% · 350
- Black or African American0.6% · 244
- American Indian and Alaska Native0.1% · 47
Timeline
Historical Census data for Reilly
Reilly 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
#845
National surname rank
Recorded bearers 40,884
+574 bearers (+1.4%)
Per 100,000 13.86
Rank movement Down 65 places
2020
#853
National surname rank
Recorded bearers 39,645
-1,239 bearers (-3.0%)
Per 100,000 13.26
Rank movement Down 8 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #780 | 40,310 | 14.94 | First available Census row | First available Census row |
| 2010 | #845 | 40,884 | 13.86 | +574 bearers (+1.4%) | Down 65 places |
| 2020 | #853 | 39,645 | 13.26 | -1,239 bearers (-3.0%) | Down 8 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 Reilly 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 | #845 | #853 | -0.9% |
| Count | 40,884 | 39,645 | -3.0% |
| Per 100K | 13.86 | 13.26 | -4.3% |
Between the 2010 and 2020 Census, the number of Reilly bearers went from 40,884 to 39,645 (-3.0% change). The surname moved down 8 positions in the national ranking, going from #845 to #853.
Notable bearers
Famous people with the surname Reilly
FAQ
Reilly surname: questions and answers
How many people in the U.S. have the surname Reilly?
Name Census estimates that about 45,462 living Americans carry the surname Reilly. Using the current population baseline, that works out to roughly 1 in 7,539 residents.
How common is Reilly?
Reilly ranks #853 in the 2020 Census surname tables and is classified on this site as "Uncommon." The Census recorded the name at a frequency of 13.26 per 100,000 residents, which is about 13 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 39,645 people with the surname Reilly. That is different from the site's living-bearer estimate (45,462), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 13.26 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 13.26 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 13 of them to have the surname Reilly.
Has Reilly become more or less common over time?
Between 2010 and 2020, the surname Reilly went from 40,884 recorded bearers to 39,645. That is a decrease of 1,239 (-3.0%). In the national ranking it fell from #845 to #853.
What does the Census say about the background of Reilly?
Among Census respondents with the surname Reilly, the largest self-reported group is White at 92.5%. The next largest groups are Hispanic (3.5%) and Two or More Races (2.4%). 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 Reilly in the 2020 Census, accounting for 92.5% (36,666 people in the source table).
What is the full ancestry breakdown?
Reilly appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (92.5%), Hispanic (3.5%), Two or More Races (2.4%). 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 Reilly (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 Reilly mean?
Descended from the Irish surname Ó Raghallaigh, meaning "descendant of Raghallach," a personal name meaning "courageous" or "valiant." 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 Reilly (13.26 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 common is the surname Reilly?
See how many Americans have the surname Reilly on HowManyOfMe.org, our sister site built around that single question.