2000
#13,675
National surname rank
Recorded bearers 2,034
First available Census row
Per 100,000 0.75
Rare Last name
Castonguay
A French topographic surname referring to someone living near a chestnut tree grove.
According to the 2020 US Census Bureau surname tables, roughly 2,298 Americans carry the last name Castonguay. That puts it at #14,358 in the national surname ranking, appearing at a frequency of 0.67 per 100,000 people (about 1 in 149,153 residents).
This page is the full Name Census profile for the Castonguay 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
2.3K
1 in 149,153
Census rank
#14,358
2020 decennial data
Per 100,000
0.7
Frequency rate
Recorded bearers
2.0K
rare in the US
Popularity narrative
The Census Bureau recorded 2,004 bearers of the surname Castonguay in its 2020 decennial surname file. At a rate of 0.67 per 100,000 residents, it holds the 14358th position in the national surname ranking.
Among Census respondents with the surname Castonguay, the largest self-reported group is White at 92.3%. The next largest groups are Two or More Races (3.6%) and Hispanic (2.8%).
Origin
Meaning and origin of Castonguay
The surname Castonguay originated in the province of Quebec, Canada in the early 17th century. It is derived from the French words "château" meaning castle and "neuf" meaning new, indicating it may have referred to someone living near a new castle or settlement. The name first appeared in records of French settlers in the Quebec region around 1635.
One of the earliest recorded instances of the Castonguay name was Jacques Castonguay, who was born in 1632 in La Rochelle, France and later immigrated to New France (now Quebec) in 1657. He married Marie Boucher in 1661 and they had several children, helping to establish the Castonguay lineage in Canada.
In the late 17th century, the name appeared in the census records of the Seigneurie de Beaupré region near Quebec City. A notable early bearer of the name was Pierre Castonguay, born in 1685, who was a farmer and landowner in this area.
Throughout the 18th and 19th centuries, the Castonguay name spread across Quebec and into other parts of Canada as the family grew. One prominent individual was Louis Castonguay, born in 1804, who was a successful merchant and businessman in Montreal.
Another noteworthy Castonguay was Rodolphe Castonguay, born in 1859, who was a lawyer and politician in Quebec. He served as a member of the Legislative Assembly of Quebec from 1892 to 1897.
In the early 20th century, Édouard Castonguay, born in 1877, was a renowned architect who designed several notable buildings in Quebec City, including the Château Frontenac hotel.
While the Castonguay name is most prevalent in Quebec and other parts of French Canada, it has also spread to other regions through immigration and descendants of the original Castonguay families.
Demographics
Ancestry and ethnicity for Castonguay
Among Census respondents with the surname Castonguay, the largest self-reported group is White at 92.3%. The next largest groups are Two or More Races (3.6%) and Hispanic (2.8%).
The bar chart below shows how Castonguay 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 Castonguay surname at the time of the 2020 Census, not any inherent property of the name itself.
- White92.3% · 1,849
- Two or more races3.6% · 73
- Hispanic or Latino2.8% · 57
- Asian and Pacific Islander0.5% · 10
- American Indian and Alaska Native0.5% · 10
- Black or African American0.2% · 5
Timeline
Historical Census data for Castonguay
Castonguay 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
#14,257
National surname rank
Recorded bearers 2,102
+68 bearers (+3.3%)
Per 100,000 0.71
Rank movement Down 582 places
2020
#14,358
National surname rank
Recorded bearers 2,004
-98 bearers (-4.7%)
Per 100,000 0.67
Rank movement Down 101 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #13,675 | 2,034 | 0.75 | First available Census row | First available Census row |
| 2010 | #14,257 | 2,102 | 0.71 | +68 bearers (+3.3%) | Down 582 places |
| 2020 | #14,358 | 2,004 | 0.67 | -98 bearers (-4.7%) | Down 101 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 Castonguay 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 | #14,257 | #14,358 | -0.7% |
| Count | 2,102 | 2,004 | -4.7% |
| Per 100K | 0.71 | 0.67 | -5.6% |
Between the 2010 and 2020 Census, the number of Castonguay bearers went from 2,102 to 2,004 (-4.7% change). The surname moved down 101 positions in the national ranking, going from #14,257 to #14,358.
FAQ
Castonguay surname: questions and answers
How many people in the U.S. have the surname Castonguay?
Name Census estimates that about 2,298 living Americans carry the surname Castonguay. Using the current population baseline, that works out to roughly 1 in 149,153 residents.
How common is Castonguay?
Castonguay ranks #14,358 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 0.67 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 2,004 people with the surname Castonguay. That is different from the site's living-bearer estimate (2,298), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 0.67 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 0.67 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 Castonguay.
Has Castonguay become more or less common over time?
Between 2010 and 2020, the surname Castonguay went from 2,102 recorded bearers to 2,004. That is a decrease of 98 (-4.7%). In the national ranking it fell from #14,257 to #14,358.
What does the Census say about the background of Castonguay?
Among Census respondents with the surname Castonguay, the largest self-reported group is White at 92.3%. The next largest groups are Two or More Races (3.6%) and Hispanic (2.8%). 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 Castonguay in the 2020 Census, accounting for 92.3% (1,849 people in the source table).
What is the full ancestry breakdown?
Castonguay appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (92.3%), Two or More Races (3.6%), Hispanic (2.8%). 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 Castonguay (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 Castonguay mean?
A French topographic surname referring to someone living near a chestnut tree grove. 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 Castonguay (0.67 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 Castonguay?
For a faster, more casual read, check HowManyOfMe.org — our sister site built around that single question.