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

Riordan, 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 Riordan surname is from the 2010 census data.

Popularity of Riordan in America

Riordan is the 4515th most popular name in America based on the data we have collected from the U.S. Census Bureau.

The Riordan surname appeared 7,848 times in the 2010 census and if you were to sample 100,000 people in the United States, approximately 3 people would have the surname Riordan.

We can also compare 2010 data for Riordan 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 Riordan

The surname Riordan is of Irish origin, having derived from the Gaelic name "Ó Riórdáin," which means "descendant of Riórdán." The name Riórdán itself is a diminutive form of the old Irish personal name Riórd, composed of the elements "rí" meaning "king" and "ard" meaning "high" or "noble."

Historically, the Riordan family hailed from County Cork in the province of Munster, Ireland. They were a prominent sept (branch of a clan) of the O'Callaghan family, who were lords of the territory known as Úibh Rathach, located near the town of Kilbrin. The earliest known record of the name Riordan appears in the Annals of Innisfallen, an Irish chronicle compiled in the 13th century, where a chieftain named Donogh O'Riordan is mentioned as having died in the year 1237.

In the 16th century, the Riordans are recorded as having held lands in the baronies of Muskerry and Duhallow in County Cork. One notable figure from this period is Donell Riordan, who was a wealthy landowner and chieftain of the Riordan sept in the late 1500s.

During the Irish Confederate Wars of the 1640s, several members of the Riordan family fought alongside the Catholic Confederates against the English Parliamentarian forces. One such individual was Dermot Riordan, who served as a captain in the Confederate army and was killed in battle in 1646.

In the late 17th century, after the Williamite War in Ireland, many Riordans were dispossessed of their lands and forced into exile or reduced to tenant farmers. One notable figure from this time was Edmond Riordan (1670-1740), a wealthy landowner and poet who wrote extensively in the Irish language.

Other notable individuals bearing the Riordan surname include:

1. Michael Riordan (1774-1858), an Irish-American soldier who fought in the War of 1812 and later became a prominent businessman in New York City.

2. Patrick Riordan (1841-1914), an Irish-born American prelate who served as the Archbishop of San Francisco from 1884 until his death.

3. Roger Riordan (1922-2006), an American chemist and pioneer in the field of nuclear magnetic resonance spectroscopy.

4. Tomás Riordan (1914-1998), an Irish Gaelic poet and writer who was a prominent figure in the Irish literary revival of the 20th century.

5. Micheal Riordan (born 1952), an Irish-American physicist and science writer, best known for his biographies of renowned scientists such as Enrico Fermi and Richard Feynman.

Race and ethnic origin of people with the last name Riordan

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

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 Riordan 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 Riordan 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 Riordan was researched and written by our team of onomatology and genealogy experts.

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

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