2000
#143,847
National surname rank
Recorded bearers 106
First available Census row
Per 100,000 0.04
Very Rare Last name
Cosgro
An Anglicized form of the Irish Gaelic surname Ó Cosgara meaning 'descendant of Cosgair'.
According to the 2020 US Census Bureau surname tables, roughly 119 Americans carry the last name Cosgro. 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 Cosgro 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 Cosgro 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 Cosgro, the largest self-reported group is White at 93.3%. The next largest groups are Two or More Races (4.8%) and Black (1.0%).
Origin
Meaning and origin of Cosgro
The surname COSGRO has its origins in Ireland, where it first appeared in the 16th century as an anglicized form of the Irish Gaelic surname "O'Cosgraidh". This name is derived from the Gaelic words "cos" meaning foot and "grádh" meaning lover or admirer, suggesting the name may have been a nickname for someone with a peculiar gait or affection for their feet.
Records show the earliest known bearer of the name was Dermot O'Cosgraidh, who lived in County Cork in the late 1500s. The surname later evolved into various spellings such as Cosgrave, Cosgrove, and the less common Cosgro.
In the 17th century, the name COSGRO appeared in the Fiants of the Tudor Sovereigns, a collection of official documents from the reign of the Tudor monarchs in Ireland. This suggests that bearers of the name held some prominence or status during this period.
One notable figure in Irish history was William Cosgrave (1880-1965), who served as the first President of the Executive Council of the Irish Free State from 1922 to 1932, effectively making him the first Prime Minister of the newly independent Ireland.
Another individual of note was John Cosgro (1738-1818), an Irish-born soldier who fought for the Continental Army during the American Revolutionary War and later became a prominent surveyor and landowner in Virginia.
In the literary world, the name is associated with James Cosgro (1920-1998), an American poet and academic who taught at various universities and published several collections of poetry throughout his lifetime.
Moving across the Atlantic, Samuel Cosgro (1801-1870) was a Canadian businessman and politician who served as a member of the Legislative Assembly of the Province of Canada in the mid-19th century.
Finally, in more recent times, Patrick Cosgro (1922-2008) was an Irish hurler who played for the Kilkenny senior team and won several prestigious hurling championships in the 1940s and 1950s.
Demographics
Ancestry and ethnicity for Cosgro
Among Census respondents with the surname Cosgro, the largest self-reported group is White at 93.3%. The next largest groups are Two or More Races (4.8%) and Black (1.0%).
The bar chart below shows how Cosgro 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 Cosgro surname at the time of the 2020 Census, not any inherent property of the name itself.
- White93.3% · 97
- Two or more races4.8% · 5
- Black or African American1.0% · 1
- Hispanic or Latino1.0% · 1
Timeline
Historical Census data for Cosgro
Cosgro 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
#153,769
National surname rank
Recorded bearers 106
+0 bearers (+0.0%)
Per 100,000 0.04
Rank movement Down 9,922 places
2020
#153,590
National surname rank
Recorded bearers 104
-2 bearers (-1.9%)
Per 100,000 0.03
Rank movement Up 179 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #143,847 | 106 | 0.04 | First available Census row | First available Census row |
| 2010 | #153,769 | 106 | 0.04 | +0 bearers (+0.0%) | Down 9,922 places |
| 2020 | #153,590 | 104 | 0.03 | -2 bearers (-1.9%) | Up 179 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 Cosgro 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 | #153,769 | #153,590 | 0.1% |
| Count | 106 | 104 | -1.9% |
| Per 100K | 0.04 | 0.03 | -13.0% |
Between the 2010 and 2020 Census, the number of Cosgro bearers went from 106 to 104 (-1.9% change). The surname moved up 179 positions in the national ranking, going from #153,769 to #153,590.
FAQ
Cosgro surname: questions and answers
How many people in the U.S. have the surname Cosgro?
Name Census estimates that about 119 living Americans carry the surname Cosgro. Using the current population baseline, that works out to roughly 1 in 2,880,289 residents.
How common is Cosgro?
Cosgro 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 Cosgro. 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 Cosgro.
Has Cosgro become more or less common over time?
Between 2010 and 2020, the surname Cosgro went from 106 recorded bearers to 104. That is a decrease of 2 (-1.9%). In the national ranking it rose from #153,769 to #153,590.
What does the Census say about the background of Cosgro?
Among Census respondents with the surname Cosgro, the largest self-reported group is White at 93.3%. The next largest groups are Two or More Races (4.8%) and Black (1.0%). 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 Cosgro in the 2020 Census, accounting for 93.3% (97 people in the source table).
What is the full ancestry breakdown?
Cosgro 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 (4.8%), Black (1.0%). 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 Cosgro (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 Cosgro mean?
An Anglicized form of the Irish Gaelic surname Ó Cosgara meaning 'descendant of Cosgair'. 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 Cosgro (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 people have the last name Cosgro?
See how many people have the surname Cosgro on HowManyOfMe.org, our sister site built around that single question.