Recorded 1888–2025 · United States
Colby was most popular in 2001, when 3,979 American babies were given the name — ranking #173 that year. In 2025 it ranked #1,146, with 515 births. Across 1880–2025 the Social Security Administration has recorded 58,155 people named Colby.
Colby first appears in Social Security Administration records in 1888, which makes it about 137 years old as a recorded American name. It has been recorded in 111 of the 138 years since.
The Social Security Administration has recorded 58,155 American births named Colby between 1880 and 2025. That is recorded US births, not a world population — it counts people issued a Social Security number at birth in the United States. Of those, roughly 56,193 are estimated to be alive today.
515 American babies were named Colby in 2025, ranking #1,146 that year.
Colby is falling. Across 2021–2025 it averaged 515 births a year, against 860 a year across 2011–2015 — a change of -40% over the decade.
Measured on recorded births. American births overall have fallen since 2007, so most established names lose births over any recent decade — a name can shed births and still hold its rank. Compare the rank above, which is measured against the other names of the same year.
Across the whole record Colby is mostly a boy’s name — 7.2% of the 58,155 Americans given it were girls and 92.8% were boys. In births since 2016 it is 10% girls and 90% boys.
Counted from every US birth the Social Security Administration recorded under this name, so it reflects use rather than opinion. A name given to fewer than five babies of one sex in a year is withheld at source and is not counted.
Roughly 56,193 Americans named Colby are alive today — 97% of everyone ever recorded with the name. The median is 25 years old, and half are between 19 and 34.
An estimate, not a count. Recorded births are carried forward through the Social Security Administration’s 2023 period life table, by age and sex. That table describes mortality in one recent year, so it credits the oldest cohorts with today’s survival rather than the harsher rates they actually lived through — the further back a name peaked, the more this will overstate how many remain. It counts people issued a Social Security number at birth, not immigrants who arrived later.
How much more common the name is in each state than across the country as a whole.
See Colby on the interactive charts
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Source: U.S.A. Social Security Administration. Years 1880–2025. namelegacy.org