2000
#11,981
National surname rank
Recorded bearers 2,392
First available Census row
Per 100,000 0.89
Rare Last name
Tiernan
An Irish surname derived from the Gaelic "Ó Tighearnáin," meaning "descendant of Tighearnán," a personal name meaning "little lord."
According to the 2020 US Census Bureau surname tables, roughly 2,696 Americans carry the last name Tiernan. That puts it at #12,570 in the national surname ranking, appearing at a frequency of 0.79 per 100,000 people (about 1 in 127,134 residents).
This page is the full Name Census profile for the Tiernan 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 Tiernan with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
2.7K
1 in 127,134
Census rank
#12,570
2020 decennial data
Per 100,000
0.8
Frequency rate
Recorded bearers
2.4K
rare in the US
Popularity narrative
The Census Bureau recorded 2,351 bearers of the surname Tiernan in its 2020 decennial surname file. At a rate of 0.79 per 100,000 residents, it holds the 12570th position in the national surname ranking.
Among Census respondents with the surname Tiernan, the largest self-reported group is White at 93.1%. The next largest groups are Hispanic (4.0%) and Two or More Races (1.9%).
Origin
Meaning and origin of Tiernan
The surname Tiernan has its origins in Ireland, where it first emerged in the medieval period. It is an Anglicized form of the Gaelic name Ó Tighearnaigh, which means "descendant of Tighearnaigh." The name Tighearnaigh itself is derived from the Irish word "tigharna," meaning "lord" or "master."
The Tiernans were a prominent family in County Roscommon, located in the western province of Connacht. They were part of the Gaelic nobility and held significant power and influence in the region. The name is first recorded in the Annals of the Four Masters, a chronicle of medieval Irish history, in the 13th century.
One of the earliest recorded individuals with the surname Tiernan was Donnchadh Ó Tighearnaigh, who was the Bishop of Elphin (a town in County Roscommon) in the late 12th century. He is mentioned in the Annals of the Four Masters under the year 1186.
Another notable figure was Aodh Ó Tighearnaigh, who was the Lord of Tir-Oilill (a territory in County Roscommon) in the 14th century. He is recorded as having played a significant role in the ongoing conflicts between the Irish clans and the Anglo-Norman settlers in Ireland during that time.
In the 16th century, the Tiernans were involved in the Irish Confederate Wars, a series of conflicts between the Irish Catholic nobility and the English Crown. Tadhg Ó Tighearnaigh, who lived around 1580, was a prominent leader in these wars and is mentioned in contemporary accounts.
The name Tiernan has also been associated with several place names in Ireland, such as Ballintiernan (Irish: Baile an Tighearnaigh, meaning "town of the Tiernan") and Killadiernan (Irish: Cill an Tighearnaigh, meaning "church of the Tiernan").
Other notable individuals with the surname Tiernan include Donal Tiernan (1783-1862), an Irish-born Australian Catholic priest and educator, and Francis Tiernan (1854-1936), an Irish-American engineer and inventor who made significant contributions to the development of the steam engine.
While the surname Tiernan has its roots in Ireland, it has since spread to various parts of the world, particularly through Irish emigration. However, its origins can be traced back to the medieval Gaelic nobility of County Roscommon, where the name first emerged and gained prominence.
Demographics
Ancestry and ethnicity for Tiernan
Among Census respondents with the surname Tiernan, the largest self-reported group is White at 93.1%. The next largest groups are Hispanic (4.0%) and Two or More Races (1.9%).
The bar chart below shows how Tiernan 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 Tiernan surname at the time of the 2020 Census, not any inherent property of the name itself.
- White93.1% · 2,189
- Hispanic or Latino4.0% · 94
- Two or more races1.9% · 45
- Asian and Pacific Islander0.6% · 13
- Black or African American0.4% · 10
Timeline
Historical Census data for Tiernan
Tiernan 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
#12,204
National surname rank
Recorded bearers 2,552
+160 bearers (+6.7%)
Per 100,000 0.87
Rank movement Down 223 places
2020
#12,570
National surname rank
Recorded bearers 2,351
-201 bearers (-7.9%)
Per 100,000 0.79
Rank movement Down 366 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #11,981 | 2,392 | 0.89 | First available Census row | First available Census row |
| 2010 | #12,204 | 2,552 | 0.87 | +160 bearers (+6.7%) | Down 223 places |
| 2020 | #12,570 | 2,351 | 0.79 | -201 bearers (-7.9%) | Down 366 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 Tiernan 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 | #12,204 | #12,570 | -3.0% |
| Count | 2,552 | 2,351 | -7.9% |
| Per 100K | 0.87 | 0.79 | -9.6% |
Between the 2010 and 2020 Census, the number of Tiernan bearers went from 2,552 to 2,351 (-7.9% change). The surname moved down 366 positions in the national ranking, going from #12,204 to #12,570.
FAQ
Tiernan surname: questions and answers
How many people in the U.S. have the surname Tiernan?
Name Census estimates that about 2,696 living Americans carry the surname Tiernan. Using the current population baseline, that works out to roughly 1 in 127,134 residents.
How common is Tiernan?
Tiernan ranks #12,570 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 0.79 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 2,351 people with the surname Tiernan. That is different from the site's living-bearer estimate (2,696), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.79 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.79 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 Tiernan.
Has Tiernan become more or less common over time?
Between 2010 and 2020, the surname Tiernan went from 2,552 recorded bearers to 2,351. That is a decrease of 201 (-7.9%). In the national ranking it fell from #12,204 to #12,570.
What does the Census say about the background of Tiernan?
Among Census respondents with the surname Tiernan, the largest self-reported group is White at 93.1%. The next largest groups are Hispanic (4.0%) and Two or More Races (1.9%). 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 Tiernan in the 2020 Census, accounting for 93.1% (2,189 people in the source table).
What is the full ancestry breakdown?
Tiernan appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (93.1%), Hispanic (4.0%), Two or More Races (1.9%). 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 Tiernan (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 Tiernan mean?
An Irish surname derived from the Gaelic "Ó Tighearnáin," meaning "descendant of Tighearnán," a personal name meaning "little lord." 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 Tiernan (0.79 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 Tiernan?
For a quick modern take, check how many people have the surname Tiernan on our sister site HowManyOfMe.org.