2010
#152,628
National surname rank
Recorded bearers 107
First available Census row
Per 100,000 0.04
Very Rare Last name
Colohan
An anglicized form of the Irish name Ó Colacháin, meaning descendant of Colochair.
According to the 2020 US Census Bureau surname tables, roughly 119 Americans carry the last name Colohan. That puts it at #153,590 in the national surname ranking, appearing at a frequency of 0.03 per 100,000 people (about 1 in 2,880,289 residents).
This page is the full Name Census profile for the Colohan 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.
Bearers in the US
119
1 in 2,880,289
Census rank
#153,590
2020 decennial data
Per 100,000
0.0
Frequency rate
Recorded bearers
104
very rare in the US
Popularity narrative
The Census Bureau recorded 104 bearers of the surname Colohan in its 2020 decennial surname file. At a rate of 0.03 per 100,000 residents, it holds the 153590th position in the national surname ranking.
Among Census respondents with the surname Colohan, the largest self-reported group is White at 93.3%. The next largest groups are Two or More Races (3.8%) and Asian/Pacific Islander (1.9%).
Origin
Meaning and origin of Colohan
The surname Colohan is believed to have originated in Ireland, specifically in the northern counties of Ulster. It is derived from the Irish Gaelic name "O'Callaghan," which means "descendant of Callaghan" or "son of the vigilant one." The earliest recorded instances of this surname can be traced back to the 12th century.
In ancient Irish records, the name is often spelled as "O'Callaghan," "O'Callachan," or "O'Callagain." These variations were due to the inconsistencies in the translation of Gaelic names into English during that time period. The name is also linked to several place names in Ireland, such as Callaghan's Cross and Callaghan's Mills, which further solidifies its Irish roots.
One of the earliest documented references to the Colohan surname 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 notable figure named Donnell O'Callaghan, who was a prominent chieftain in County Cork in the late 13th century.
Another notable individual bearing this surname was Edmund Colohan, also known as Edmund O'Callaghan, who lived in the 16th century. He was a renowned Irish scholar and historian, known for his work "The Green Book of Munster," which documented the history and genealogy of several prominent Irish families.
In the 17th century, during the Confederate Wars of Ireland, a man named Dermot Colohan, or Dermot O'Callaghan, played a significant role as a military commander. He fought alongside the Irish Confederate forces against the English Parliamentary forces led by Oliver Cromwell.
Another individual of note was Jeremiah Colohan, born in 1758 in County Tipperary, Ireland. He was a prominent Catholic priest and educator who founded several schools in Ireland during a time when Catholic education was heavily restricted.
In the 19th century, a man named Daniel Colohan, born in 1820, was a prominent Irish-American businessman and philanthropist. He immigrated to the United States and became a successful entrepreneur, eventually establishing the Colohan Foundation, which supported various charitable causes in both Ireland and America.
While the Colohan surname has its roots in Ireland, it has since spread to various parts of the world, particularly through Irish immigration to countries like the United States, Canada, and Australia. However, the earliest recorded instances and historical figures associated with this name can be traced back to its Irish origins, spanning several centuries.
Demographics
Ancestry and ethnicity for Colohan
Among Census respondents with the surname Colohan, the largest self-reported group is White at 93.3%. The next largest groups are Two or More Races (3.8%) and Asian/Pacific Islander (1.9%).
The bar chart below shows how Colohan 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 Colohan surname at the time of the 2020 Census, not any inherent property of the name itself.
- White93.3% · 97
- Two or more races3.8% · 4
- Asian and Pacific Islander1.9% · 2
- American Indian and Alaska Native1.0% · 1
Timeline
Historical Census data for Colohan
Colohan 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
#153,590
National surname rank
Recorded bearers 104
-3 bearers (-2.8%)
Per 100,000 0.03
Rank movement Down 962 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2010 | #152,628 | 107 | 0.04 | First available Census row | First available Census row |
| 2020 | #153,590 | 104 | 0.03 | -3 bearers (-2.8%) | Down 962 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 Colohan 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 | #152,628 | #153,590 | -0.6% |
| Count | 107 | 104 | -2.8% |
| Per 100K | 0.04 | 0.03 | -13.0% |
Between the 2010 and 2020 Census, the number of Colohan bearers went from 107 to 104 (-2.8% change). The surname moved down 962 positions in the national ranking, going from #152,628 to #153,590.
FAQ
Colohan surname: questions and answers
How many people in the U.S. have the surname Colohan?
Name Census estimates that about 119 living Americans carry the surname Colohan. Using the current population baseline, that works out to roughly 1 in 2,880,289 residents.
How common is Colohan?
Colohan ranks #153,590 in the 2020 Census surname tables and is classified on this site as "Very Rare." The Census recorded the name at a frequency of 0.03 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 104 people with the surname Colohan. That is different from the site's living-bearer estimate (119), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.03 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.03 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 Colohan.
Has Colohan become more or less common over time?
Between 2010 and 2020, the surname Colohan went from 107 recorded bearers to 104. That is a decrease of 3 (-2.8%). In the national ranking it fell from #152,628 to #153,590.
What does the Census say about the background of Colohan?
Among Census respondents with the surname Colohan, the largest self-reported group is White at 93.3%. The next largest groups are Two or More Races (3.8%) and Asian/Pacific Islander (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 Colohan in the 2020 Census, accounting for 93.3% (97 people in the source table).
What is the full ancestry breakdown?
Colohan appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (93.3%), Two or More Races (3.8%), Asian/Pacific Islander (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 Colohan (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 Colohan mean?
An anglicized form of the Irish name Ó Colacháin, meaning descendant of Colochair. 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 Colohan (0.03 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 Colohan?
For a faster, more casual read, check HowManyOfMe.org — our sister site built around that single question.