Mapping Irish Surnames

Surnames from Ireland abound in the United States, even after subsequent waves of immigration from other parts of the world. According to the Census Bureau, around 33 million Americans claim Irish ancestry. That’s 10.1 percent of the U.S. population — and more than five times Ireland's current population of 6.6 million.

The abundance of Irish names in America is in large part a result of the Great Famine of 1846-49. Much of Ireland's impoverished rural population had come to depend for sustenance almost exclusively on the potato — a crop that, ironically, originated in the New World. A water mold called Phytophthora arrived from North America in 1845 and caused much of Ireland's potato crop to rot in the fields over several successive years.

About a million people died of causes related to starvation, and hundreds of thousands more fled the country. Ireland's population in 1841 was 8.53 million; by 1926 it was under three million. Immigration to the U.S. soared.

Those with Irish ancestry might be curious to know from which part of Ireland their forbearers hailed. "His face is a map of Ireland," people often remark of individuals with freckled cheeks, red hair, and prominent features. That's all well and good, but perhaps more informative is a map of the face of Ireland, with surnames applied to regions of origin.

Thus we present the map below. Whether exploring by search or zoom and pan, you'll find Finns and Fergusons, MacDermotts and McLaughlins galore.

A caveat: The map is informative, but not necessarily authoritative. It's based on a late-19th-century report that cataloged surnames by county; if five or more children born within a county shared a surname, then that name appeared on the list.

We tend to assume that surnames are of ancient origin. In fact, they were quite fluid from generation to generation in Ireland (and elsewhere in Europe) until about 900-600 years ago. As Leslie Lang writes on Ancestry.com, "Mac" was often added to a name to denote "son of." "O'" indicated "grandson of" or "descendent of."

Names were in Gaelic, of course; the surnames that are familiar to us are largely Anglicized, a result of increasing British influence (read: persecution) from about 1500 on. Murphy, for instance (the most common Irish surname), is derived from Ó Murchadha, which in turn is derived from Murchadh, meaning sea-warrior.

At any rate, regardless of whether your ancestry is Irish or Iraqi, we hope you'll enjoy perusing the map.