2000
#3,015
National surname rank
Recorded bearers 11,023
First available Census row
Per 100,000 4.09
Uncommon Last name
Colby
From the Old Norse byname Koli, meaning "coal black," likely referring to someone with dark features or hair.
According to the 2020 US Census Bureau surname tables, roughly 12,116 Americans carry the last name Colby. That puts it at #3,336 in the national surname ranking, appearing at a frequency of 3.53 per 100,000 people (about 1 in 28,289 residents).
This page is the full Name Census profile for the Colby 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 Colby with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
12K
1 in 28,289
Census rank
#3,336
2020 decennial data
Per 100,000
3.5
Frequency rate
Recorded bearers
11K
uncommon in the US
Popularity narrative
The Census Bureau recorded 10,566 bearers of the surname Colby in its 2020 decennial surname file. At a rate of 3.53 per 100,000 residents, it holds the 3336th position in the national surname ranking.
Among Census respondents with the surname Colby, the largest self-reported group is White at 89.9%. The next largest groups are Two or More Races (3.6%) and Hispanic (3.6%).
Origin
Meaning and origin of Colby
The surname Colby has its origins in the Old Norse language, where it was derived from the word "kolr," meaning "coal" or "black." It first emerged in England during the 11th century, following the Norman Conquest.
Colby is believed to have originated as a place name, referring to settlements or villages with a connection to coal mining or coal-blackened landscapes. The earliest known record of the name appears in the Domesday Book of 1086, where it is listed as "Coleby" in Lincolnshire.
The name spread throughout various regions of England, particularly in the counties of Yorkshire, Lincolnshire, and Nottinghamshire. Over time, it evolved into various spellings, including Colby, Colbie, Colbey, and Coulby.
One of the earliest recorded individuals with the surname Colby was Sir John Colby (c. 1335-1405), a prominent English soldier and landowner who served as a knight during the Hundred Years' War. Another notable figure was Samuel Colby (1616-1687), a Puritan settler who migrated from England to Massachusetts Bay Colony in the 17th century.
In the 18th century, Thomas Colby (1784-1857) gained recognition as a renowned English landscape painter, known for his depictions of rural scenes. Later, in the 19th century, Frank Moore Colby (1865-1925) made his mark as an American editor and publisher, serving as the editor-in-chief of the New International Encyclopedia.
Another prominent individual with the Colby surname was William Egan Colby (1920-1996), an American diplomat and intelligence officer who served as the Director of Central Intelligence from 1973 to 1976.
While the Colby surname has its roots in England, it has since spread to various parts of the world, including the United States, Canada, and Australia, where it continues to be carried by numerous individuals.
Demographics
Ancestry and ethnicity for Colby
Among Census respondents with the surname Colby, the largest self-reported group is White at 89.9%. The next largest groups are Two or More Races (3.6%) and Hispanic (3.6%).
The bar chart below shows how Colby 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 Colby surname at the time of the 2020 Census, not any inherent property of the name itself.
- White89.9% · 9,496
- Two or more races3.6% · 380
- Hispanic or Latino3.6% · 378
- Black or African American1.6% · 174
- Asian and Pacific Islander1.0% · 103
- American Indian and Alaska Native0.3% · 35
Timeline
Historical Census data for Colby
Colby 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
#3,204
National surname rank
Recorded bearers 11,278
+255 bearers (+2.3%)
Per 100,000 3.82
Rank movement Down 189 places
2020
#3,336
National surname rank
Recorded bearers 10,566
-712 bearers (-6.3%)
Per 100,000 3.53
Rank movement Down 132 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #3,015 | 11,023 | 4.09 | First available Census row | First available Census row |
| 2010 | #3,204 | 11,278 | 3.82 | +255 bearers (+2.3%) | Down 189 places |
| 2020 | #3,336 | 10,566 | 3.53 | -712 bearers (-6.3%) | Down 132 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 Colby 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 | #3,204 | #3,336 | -4.1% |
| Count | 11,278 | 10,566 | -6.3% |
| Per 100K | 3.82 | 3.53 | -7.5% |
Between the 2010 and 2020 Census, the number of Colby bearers went from 11,278 to 10,566 (-6.3% change). The surname moved down 132 positions in the national ranking, going from #3,204 to #3,336.
FAQ
Colby surname: questions and answers
How many people in the U.S. have the surname Colby?
Name Census estimates that about 12,116 living Americans carry the surname Colby. Using the current population baseline, that works out to roughly 1 in 28,289 residents.
How common is Colby?
Colby ranks #3,336 in the 2020 Census surname tables and is classified on this site as "Uncommon." The Census recorded the name at a frequency of 3.53 per 100,000 residents, which is about 4 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 10,566 people with the surname Colby. That is different from the site's living-bearer estimate (12,116), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 3.53 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 3.53 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 4 of them to have the surname Colby.
Has Colby become more or less common over time?
Between 2010 and 2020, the surname Colby went from 11,278 recorded bearers to 10,566. That is a decrease of 712 (-6.3%). In the national ranking it fell from #3,204 to #3,336.
What does the Census say about the background of Colby?
Among Census respondents with the surname Colby, the largest self-reported group is White at 89.9%. The next largest groups are Two or More Races (3.6%) and Hispanic (3.6%). 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 Colby in the 2020 Census, accounting for 89.9% (9,496 people in the source table).
What is the full ancestry breakdown?
Colby appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (89.9%), Two or More Races (3.6%), Hispanic (3.6%). 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 Colby (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 Colby mean?
From the Old Norse byname Koli, meaning "coal black," likely referring to someone with dark features or hair. 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 Colby (3.53 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 Colby?
Want to know how common the surname Colby is? HowManyOfMe.org, our sister site, puts the living-bearer count front and centre.