Find out how popular the last name Cassidy is in the United States and learn more about the meaning, history, and race and ethnic origin of people in America who are named Cassidy.

Cassidy, like all of the last names we have data for, is identified by the U.S. Census Bureau as a surname which has more than 100 occurrences in the United States in the Decennial Census survey. The most recent statistics we have for the Cassidy surname is from the 2010 census data.

Popularity of Cassidy in America

Cassidy is the 1325th most popular name in America based on the data we have collected from the U.S. Census Bureau.

The Cassidy surname appeared 26,590 times in the 2010 census and if you were to sample 100,000 people in the United States, approximately 9 people would have the surname Cassidy.

We can also compare 2010 data for Cassidy to data from the previous census in 2000. The table below contains all of the statistics for both years in a side-by-side comparison.

The history of the last name Cassidy

The surname Cassidy is an anglicized form of the Irish Gaelic name O'Caiside. It originated in Ireland during the 11th century, primarily in County Fermanagh. The name is derived from the Gaelic personal name Caiside, which means "curly-headed" or "curly-haired."

O'Caiside was an important Irish clan, known for their involvement in the Irish Confederate Wars of the 17th century. The name can be found in various ancient Irish manuscripts and records, including the Annals of the Four Masters, which document the history of Ireland from the earliest times to the 17th century.

One of the earliest recorded instances of the surname Cassidy dates back to the 13th century, when a man named Gillebertus O'Caiside was mentioned in the Annals of Ulster in 1261. The name was also found in the Fiants of the Tudor Sovereigns, a collection of records from the reigns of Henry VIII, Edward VI, and Mary I.

The Cassidy surname has been associated with several notable individuals throughout history. One of the earliest was Sir Thomas Cassidy (c. 1570-1651), an Irish soldier and landowner who fought for the English Crown during the Irish Confederate Wars. Another prominent figure was Patrick Cassidy (1756-1828), an Irish rebel leader who participated in the Irish Rebellion of 1798.

In the 19th century, John Cassidy (1809-1865) was a prominent Irish-American businessman and politician who served as the 84th Mayor of New York City from 1858 to 1859. William Cassidy (1815-1873) was an Irish-American prelate who served as the Bishop of Brooklyn from 1853 until his death.

More recently, Brendan Cassidy (1924-2016) was an Irish Jesuit priest, theologian, and author, known for his work on Thomas Aquinas and Catholic social teaching. Shaun Cassidy (born 1958) is an American actor, writer, and producer, best known for his roles in the 1970s television series "The Hardy Boys" and "The Hardy Boys/Nancy Drew Mysteries."

Race and ethnic origin of people with the last name Cassidy

We also have some data on the ancestry of people with the surname Cassidy.

The below race categories are the modified race categories used in the Census Bureau's population estimates program. All people were categorized into six mutually exclusive racial and Hispanic origin groups:

1. White only
2. Black only
3. American Indian and Alaskan Native only
4. Asian and Pacific Islander only
5. Hispanic
6. Two or More Races

For the most recent 2010 census data, the race/ethnic origin breakdown for Cassidy was:

Note: Any fields showing (S) means the data was suppressed for privacy so that the data does not in any way identify any specific individuals.

Since we have data from the previous census in 2000, we can also compare the values to see how the popularity of Cassidy has changed in the 10 years between the two census surveys.

Data source

The last name data and ethnic breakdown of last names is sourced directly from the Decennial Census survey, conducted every 10 years by the United States Census Bureau.

The history and meaning of the name Cassidy was researched and written by our team of onomatology and genealogy experts.

If you have a correction or suggestion to improve the history of Cassidy, please contact us.

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