2000
#32,338
National surname rank
Recorded bearers 671
First available Census row
Per 100,000 0.25
Very Rare Last name
Kilday
An anglicized form of the Irish surname Ó Cillideadha, meaning "descendent of Cillideadh" (a personal name).
According to the 2020 US Census Bureau surname tables, roughly 744 Americans carry the last name Kilday. That puts it at #36,981 in the national surname ranking, appearing at a frequency of 0.22 per 100,000 people (about 1 in 460,691 residents).
This page is the full Name Census profile for the Kilday 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 Kilday with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
744
1 in 460,691
Census rank
#36,981
2020 decennial data
Per 100,000
0.2
Frequency rate
Recorded bearers
649
very rare in the US
Popularity narrative
The Census Bureau recorded 649 bearers of the surname Kilday in its 2020 decennial surname file. At a rate of 0.22 per 100,000 residents, it holds the 36981st position in the national surname ranking.
Among Census respondents with the surname Kilday, the largest self-reported group is White at 94.3%. The next largest groups are Two or More Races (2.6%) and Hispanic (2.5%).
Origin
Meaning and origin of Kilday
The surname Kilday originated in Ireland and has its roots in the Gaelic language. It is believed to have derived from the Irish words "Cill" meaning church, and "daith" meaning color or hue, potentially referring to someone who lived near a church of a particular color or shade.
One of the earliest recorded instances of the name dates back to the 16th century, when a Thomas Kilday was mentioned in the Annals of the Four Masters, a chronicle of medieval Irish history compiled in the early 17th century.
The Kilday name can also be traced back to County Sligo in the northwestern region of Ireland, where it was concentrated in the area around Ballymote and its surrounding parishes.
In the 17th century, a notable figure named James Kilday (1640-1715) was a prominent merchant and landowner in County Sligo. He played a significant role in the economic and social life of the region during that time.
Another historical figure with the Kilday surname was John Kilday (1714-1789), a Irish-born merchant and ship owner who settled in the American colonies. He established a successful trading business in Philadelphia and was a prominent member of the city's Irish community.
During the 19th century, the Kilday name gained recognition through the works of Irish poet and playwright Samuel Kilday (1822-1891). His poems and plays often depicted the lives and struggles of the Irish working class, earning him a reputation as a voice for the common people.
In the field of education, Mary Kilday (1856-1934) was a pioneering educator and advocate for women's rights in Ireland. She founded several schools and played a crucial role in promoting education for girls in her home country.
Another notable figure was Patrick Kilday (1876-1952), a Irish-American politician who served as a member of the United States House of Representatives from Texas in the early 20th century.
While the Kilday name has its roots in Ireland, it has since spread to various parts of the world, with individuals bearing this surname making significant contributions in various fields throughout history.
Demographics
Ancestry and ethnicity for Kilday
Among Census respondents with the surname Kilday, the largest self-reported group is White at 94.3%. The next largest groups are Two or More Races (2.6%) and Hispanic (2.5%).
The bar chart below shows how Kilday 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 Kilday surname at the time of the 2020 Census, not any inherent property of the name itself.
- White94.3% · 612
- Two or more races2.6% · 17
- Hispanic or Latino2.5% · 16
- Asian and Pacific Islander0.5% · 3
- American Indian and Alaska Native0.2% · 1
Timeline
Historical Census data for Kilday
Kilday 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
#34,032
National surname rank
Recorded bearers 668
-3 bearers (-0.4%)
Per 100,000 0.23
Rank movement Down 1,694 places
2020
#36,981
National surname rank
Recorded bearers 649
-19 bearers (-2.8%)
Per 100,000 0.22
Rank movement Down 2,949 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #32,338 | 671 | 0.25 | First available Census row | First available Census row |
| 2010 | #34,032 | 668 | 0.23 | -3 bearers (-0.4%) | Down 1,694 places |
| 2020 | #36,981 | 649 | 0.22 | -19 bearers (-2.8%) | Down 2,949 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 Kilday 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 | #34,032 | #36,981 | -8.7% |
| Count | 668 | 649 | -2.8% |
| Per 100K | 0.23 | 0.22 | -5.6% |
Between the 2010 and 2020 Census, the number of Kilday bearers went from 668 to 649 (-2.8% change). The surname moved down 2,949 positions in the national ranking, going from #34,032 to #36,981.
FAQ
Kilday surname: questions and answers
How many people in the U.S. have the surname Kilday?
Name Census estimates that about 744 living Americans carry the surname Kilday. Using the current population baseline, that works out to roughly 1 in 460,691 residents.
How common is Kilday?
Kilday ranks #36,981 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.22 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 649 people with the surname Kilday. That is different from the site's living-bearer estimate (744), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.22 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.22 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 Kilday.
Has Kilday become more or less common over time?
Between 2010 and 2020, the surname Kilday went from 668 recorded bearers to 649. That is a decrease of 19 (-2.8%). In the national ranking it fell from #34,032 to #36,981.
What does the Census say about the background of Kilday?
Among Census respondents with the surname Kilday, the largest self-reported group is White at 94.3%. The next largest groups are Two or More Races (2.6%) and Hispanic (2.5%). 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 Kilday in the 2020 Census, accounting for 94.3% (612 people in the source table).
What is the full ancestry breakdown?
Kilday appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (94.3%), Two or More Races (2.6%), Hispanic (2.5%). 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 Kilday (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 Kilday mean?
An anglicized form of the Irish surname Ó Cillideadha, meaning "descendent of Cillideadh" (a personal name). 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 Kilday (0.22 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 Kilday?
HowManyOfMe.org, our sister site, answers that with the living-bearer count in one glance.