Casey As An Irish Last Name

This article looks at how common Casey is as a last name in Ireland and the United States from the 19th century to the present day.

You’ll learn the meaning and origins of the Casey surname while exploring some notable and famous people that held it.

I use census records, emigration lists, and military archives to uncover fascinating patterns. If you’re studying your genealogy, check out my sources at the end of the post so you can do your own research.

How Common Is Casey As A Surname In Ireland?

Ireland does not disclose current statistics on surnames in much detail. The most that we get is the top ten last names in birth registrations for the previous year. Casey isn’t common enough to break into this list.

So, I had to look elsewhere for population estimates. Thankfully, an Irish genealogist researched the prevalence of Irish surnames through national phone directories published in the 1990s. Seán Murphy’s estimates aren’t as robust as a census but give a good broad estimate.

Casey was ranked 75 in the top one hundred names in this decade with a total of 11,200 entries.

This graphic shows how it ranks compared to the 1st, 33rd, 66th, and 100th entries in the survey:

Casey Ireland 1990s

Casey In The Early 1900s

The only complete Irish censuses that are available to the general public are those from the years 1901 and 1911. They offer two detailed snapshots of the population.

So, let’s focus on the early 1900s.

I used online archives to calculate the total numbers by surname. I consider these estimates due to some percentage of transcription errors. So, I’ve rounded the numbers to the nearest fifty.

There were 9,200 residents named Casey on the island in 1911.

Ten years earlier, Casey had about 9,300 residents in the 1901 census.

Population Estimates In The 1890s

A study of Irish surnames was conducted in 1890 by the head of the Civil Registrations Office. It was published as a “Special Report on Surnames In Ireland.”

The survey estimated that there were about 11,300 people named Casey in the country.

Emigration To America After The Irish Famine

The Irish diaspora is large and widespread with a significant number of people emigrating to other parts of the globe. The destinations traditionally have been England, the U.S., Canada, and Australia. Emigrants were driven by various factors like political unrest, poverty, and food scarcity.

The Great Irish Famine, which happened from 1845 to 1852, caused the largest wave of emigration. The potato blight was a disaster for Ireland because it destroyed the main food source for a large proportion of the people.

I reviewed the Casey name in the shipping passenger lists arriving in New York during this period. The departures were from both Ireland and England.

The graph below shows how the numbers rose and fell in the years after the famine. You can see how the number peaks after six years of hardship.

Casey emigration after the famine

With that explanation out of the way, let’s look at how Casey ranks in America.

How Common Is Casey As A Last Name In The U.S?

Based on the 2010 U.S. census, the name Casey ranks about 504 among Irish names in America with 66,556 bearers.

Although the 2010 census has exact numbers and rankings, the rank I assign here is my estimate. If you’re curious about how I got there, here’s a brief explanation…

Estimating Rank In The United States

Historically, some Irish families with Gaelic surnames took English-sounding names as translations under the influence of colonization.

As these names also have English origins, they will have been brought to the United States by both British and Irish immigrants. Because the census doesn’t ask about specific European origin (e.g. England vs Ireland), it’s impossible to identify the proportion with Irish heritage.

I reviewed the census to identify which names are predominantly Irish in origin. In order to estimate the relative rankings of “Irish” names, I’ve mostly excluded surnames that have varying origins.

Casey In Historic Census Years

It is fascinating to examine how the prevalence of a surname shifts over the course of time in a country as young as the United States. As well as immigration, this reflects other demographic shifts across the nation. Factors include higher child mortality rates and longer life expectancy.

The historic census records have been transcribed and digitized. I used online archives to run counts of surname populations.

But the totals can’t be exactly accurate due to transcription errors. So, I’ve rounded the numbers to the nearest 50 in the graph below.

This picture shows the numbers every twenty years from 1860 to 1940:

how common was Casey in the U.S. between 1860 and 1940

These are the numbers in the graph:

  • 1860: 9,700
  • 1880: 19,550
  • 1900: 27,100
  • 1920: 32,600
  • 1940: 39,750

Casey In World War II

About 8.3 million men and women enlisted in the U.S. Army during the Second World War. Many were of Irish heritage, and some were born in Ireland.

There were registration records for 2,392 soldiers named Casey who enlisted between 1938 and 1946.

There were 37 who were born in Ireland.

Casey Surname: Meaning And Origin

Casey comes from the Gaelic name Ó Cathasaigh, which means “descendant of Cathasach.”

The personal name Cathasach gets its meaning from two Gaelic words: “cath” means a battle and “sach” refers to being watchful or vigilant. The original bearers of the name were likely families of a warrior who was vigilant in conflict.

There are several notable Casey families in early Ireland. One family were chieftains in what is now North Dublin and part of Meath until their lands were taken during the Anglo-Norman Invasion. The Norman knight Hugh de Lacy was given the Kingdom of Meath by Henry II.

Famous Or Historic People Named Casey

Here are some notable people with the family name:

  • Samuel Casey (about 1723-1773): a talented silversmith who was sentenced to death in Rhode Island for counterfeiting. A mob broke into the jail and freed Casey with at least three others. His silverware is displayed in several museums.
  • Silas Casey (1807-1882): a brigadier general during the Civil War, Silas Casey wrote the Union Army’s manual on infantry tactics. His son Silas became a rear admiral.
  • John Casey (1820-1891): Limerick-born geometer who formulated Casey’s Theorem which concerns four adjacent circles.
  • Seán O’Casey (1880-1964): renowned Irish playwright and socialist activist. His best known plays are set amongst the working class during the Easter Rising and subsequent Irish Civil War.

More Irish Names Beginning With C


Casey As A Last Name

External Research

The Ireland 1990s estimates are from Seán J. Murphy’s research paper.

The population estimates of 1890 are based on the “Special Report on Surnames in Ireland“, published in 1909.

The population figures for the 2010 U.S. Census come from a file provided by the U.S. Census Bureau.

Internal Research

Some of the population numbers are based on my own research and calculations using online archives. I’ve rounded those numbers to the nearest 50 to account for transcription errors and other technical issues with online databases of this type.

The Irish census estimates for 1901 and 1911 are my calculations based on the Irish National Archives

I plotted the emigration figures from 1845 to 1854 based on calculations from the archives of the New York Passenger Lists (1820-1957).