St. Patrick’s Day Maps and Geography

Caitlin Dempsey


St. Patrick’s is a day when everyone is welcome to claim a little Irishness about them.  Celebrated on the day of this patron saint of Ireland’s birthday, March 17th has transcended its religious origins and become a day to wear green, speak in a fake Irish brogue, and eating corned beef.  

The U.S. Census puts out special statistics each year in honor of Irish American Heritage Month and St. Patrick’s Day.  According to the 2020 American Community Survey, over 30.4 million or 9.2% Americans claim Irish ancestry.  This amounts to about six times the current population of Ireland which is 4.95 million.

Mapping Irish Surnames

Esri offers a map story entitled “Mapping the Emerald Isle: a geo-genealogy of Irish surnames.”  The map explores over 2,500 Irish surnames by county from an Irish census dating back to 1890 that recorded births during that year.  

Type in an Irish surname and see what counties recorded a birth that year.  Typing in “Dempsey” yielded ten in Offaly, and one each in counties Kildare and Laois.  

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Dempsey is the anglicized version of O’Diomasaighe coming from the Irish word “diomusach” meaning proud, haughty, or arrogant.  Typing in “O’Dempsey” yielded four more results, with one birth each in counties Offaly, Kildare, Laois, and Roscommon.

Interactive map of Irish surnames from 1890. Source: Esri.
Interactive map of Irish surnames from 1890. Source: Esri.

The interactive map was developed from a study done in 2009 by Drs. Kenneth Field and Linda Beale which looked at the use of GIS to create a “visual interpretation of the spatial and quantitative distribution of birth data from the 1890 Irish census of population.”  

The resulting “Geo-Genealogy of Irish Surnames” is a densely typeset map with label symbol scaling of Irish surnames proportional to the number of births recorded in the 1980 census.  Kenneth Field has a post about the process on Esri’s Mapping Center blog and a PDF of the Irish Surnames map (36 MB in size) is also available.

Map of Irish Surnames from 1890 Census.
Map of Irish Surnames from 1890 Census.

Geography of St. Patrick’s Day

Within the United States, the U.S. Census reports (2012) that there are seven places within the United States that contain the name Shamrock:

Mount Gay-Shamrock, W.Va., and Shamrock, Texas, were the most populous, with 1,779 and 1,910 residents, respectively. Shamrock Lakes, Ind., had 231 residents and Shamrock, Okla., 101, and three Shamrock Townships in Minnesota, Nebraska and Missouri had populations of 1,272, 413 and 40, respectively.

There are sixteen places in the U.S. named after the Irish capital.  Of these, Dublin, California is the most populated with a count of 46,036.

Other Irish placenames included  Emerald Isle, North Carolina, and “the township of Irishtown, Illinois, several places or townships named Clover (in South Carolina, Illinois, Minnesota, Pennsylvania and Wisconsin) and the township of Cloverleaf, Minnesota.”

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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.