2010
#125,282
National surname rank
Recorded bearers 137
First available Census row
Per 100,000 0.05
Very Rare Last name
Dempsy
An Anglicized spelling of the Irish surname Ó Diomasaigh, meaning "descendant of the proud or noble one".
According to the 2020 US Census Bureau surname tables, roughly 133 Americans carry the last name Dempsy. That puts it at #145,028 in the national surname ranking, appearing at a frequency of 0.04 per 100,000 people (about 1 in 2,577,100 residents).
This page is the full Name Census profile for the Dempsy 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 Dempsy with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
133
1 in 2,577,100
Census rank
#145,028
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
116
very rare in the US
Popularity narrative
The Census Bureau recorded 116 bearers of the surname Dempsy in its 2020 decennial surname file. At a rate of 0.04 per 100,000 residents, it holds the 145028th position in the national surname ranking.
Among Census respondents with the surname Dempsy, the largest self-reported group is White at 75.9%. The next largest groups are Black (8.6%) and Hispanic (8.6%).
Origin
Meaning and origin of Dempsy
The surname Dempsy has its origins in Ireland, where it emerged during the Middle Ages as an Anglicized form of the Gaelic name Ó Díomasaigh, meaning "descendant of Díomasach." Díomasach is derived from the Old Irish word "díomais," meaning "proud" or "arrogant."
This surname is believed to have originated in County Laois, a region in the province of Leinster, Ireland. It was first recorded in its Gaelic form, Ó Díomasaigh, during the 13th century.
One of the earliest recorded instances of the name appears in the Annals of the Four Masters, a chronicle of medieval Irish history. In 1318, the Annals mention a man named William O'Dempsy, who was described as a "learned historian and poet."
The surname's spelling evolved over time, with variations such as Dempsie, Dempsey, Dempsy, and Dempseigh appearing in various historical records. During the 16th and 17th centuries, many Irish families Anglicized their surnames to conform to English naming conventions, leading to the emergence of the spelling "Dempsy."
One notable bearer of the name was Terence Dempsy, a Catholic priest and writer who lived in the late 16th century. He is best known for his work "The Imitation of Christ," which was published in 1583.
Another prominent figure was Michael Dempsy, a lawyer and politician who served as a member of the Irish Parliament in the early 18th century. He was born in 1672 and died in 1735.
In the 19th century, a famous American boxer named Jack Dempsy, also known as "The Manassa Mauler," rose to prominence. He was born in 1895 and became the world heavyweight boxing champion in 1919, holding the title until 1926.
Another notable individual was Sir Nigel Dempsy, a British diplomat and ambassador who served during the 20th century. He was born in 1910 and played a crucial role in negotiating the Camp David Accords between Egypt and Israel in 1978.
Finally, the name Dempsy has also been associated with several places in Ireland, such as Dempsy's Rath in County Laois and Dempsy's Bridge in County Kilkenny, further highlighting the surname's deep roots in Irish history and geography.
Demographics
Ancestry and ethnicity for Dempsy
Among Census respondents with the surname Dempsy, the largest self-reported group is White at 75.9%. The next largest groups are Black (8.6%) and Hispanic (8.6%).
The bar chart below shows how Dempsy 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 Dempsy surname at the time of the 2020 Census, not any inherent property of the name itself.
- White75.9% · 88
- Black or African American8.6% · 10
- Hispanic or Latino8.6% · 10
- Two or more races3.4% · 4
- American Indian and Alaska Native2.6% · 3
- Asian and Pacific Islander0.9% · 1
Timeline
Historical Census data for Dempsy
Dempsy appears in 2 published Census surname files: 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2020
#145,028
National surname rank
Recorded bearers 116
-21 bearers (-15.3%)
Per 100,000 0.04
Rank movement Down 19,746 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2010 | #125,282 | 137 | 0.05 | First available Census row | First available Census row |
| 2020 | #145,028 | 116 | 0.04 | -21 bearers (-15.3%) | Down 19,746 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 Dempsy 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 | #125,282 | #145,028 | -15.8% |
| Count | 137 | 116 | -15.3% |
| Per 100K | 0.05 | 0.04 | -22.4% |
Between the 2010 and 2020 Census, the number of Dempsy bearers went from 137 to 116 (-15.3% change). The surname moved down 19,746 positions in the national ranking, going from #125,282 to #145,028.
FAQ
Dempsy surname: questions and answers
How many people in the U.S. have the surname Dempsy?
Name Census estimates that about 133 living Americans carry the surname Dempsy. Using the current population baseline, that works out to roughly 1 in 2,577,100 residents.
How common is Dempsy?
Dempsy ranks #145,028 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.04 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 116 people with the surname Dempsy. That is different from the site's living-bearer estimate (133), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.04 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.04 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 Dempsy.
Has Dempsy become more or less common over time?
Between 2010 and 2020, the surname Dempsy went from 137 recorded bearers to 116. That is a decrease of 21 (-15.3%). In the national ranking it fell from #125,282 to #145,028.
What does the Census say about the background of Dempsy?
Among Census respondents with the surname Dempsy, the largest self-reported group is White at 75.9%. The next largest groups are Black (8.6%) and Hispanic (8.6%). 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 Dempsy in the 2020 Census, accounting for 75.9% (88 people in the source table).
What is the full ancestry breakdown?
Dempsy appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (75.9%), Black (8.6%), Hispanic (8.6%). 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 Dempsy (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 Dempsy mean?
An Anglicized spelling of the Irish surname Ó Diomasaigh, meaning "descendant of the proud or noble one". 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 Dempsy (0.04 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 Dempsy?
HowManyOfMe.org, our sister site, answers that with the living-bearer count in one glance.