Mac, Mc and ‘O’ : Irish names in America The Irish Roots Cafe
Irish Names in America Mac, Mc, O

Source for more information:
“Names That Begin with Mac, Mc, and O
in Ireland, Scotland and America”

Irish Names
Today I thought we would take a look at
Irish names that begin with Mac and ‘O’.
I am taking the stats from a book I wrote
several years back (see link above).

Festival Questions
Just returning yesterday from the Dublin,
Ohio Irish Festival, I handled many
questions on family names. Each year
I repeat the mantra “Mac and Mc” stand
for the same thing, and mean ‘son of’.
The ‘O’ before Irish names means ‘grandson’
of. (though I was told as a child it meant
we were chieftains…).
Of course today we recognize it as meaning
‘descended from’, and sometimes stretch
it into meaning follower of.

The Apostrophe
That old apostrophe that causes so many
computer programs trouble, is actually
the remnant of the ‘Fada’, the old Irish
accent mark found over the ‘O’ in the
Irish language. Seems we just were not
willing to give that up !

Names From the Book
I quote my own work below:
“We now move to the 1790 U.S. Census, and
take inventory of the most common Mac/Mc names
given in that document. Some grouping of names
has taken place inthe analysis of that census,
and most are accurate. There are a few errors,
like equating McDonogh with (O) Donoghue.
The count included various ways to spell the name,
all were prefixed Mac or Mc. The number following
the name is all other family members outside of
the head of household. Below are the top 30 Mac names.

Most Numerous Mac Names in Early America
1. McDonald (1291)
2. McLean, McClaine (1265)
3. McKee (1031)
4. McCoy (994)
5. McClelland (873)
6. McDaniel (858)
7. McIntire (851)
8. McNiel (764)
9. McKinney, McKenna (738)
10. McMullen (723) not McMillen
11. McFarland (721)
12. McClure (712)
13. McCulloch (703)
14. McDowel (587)
15. McGee (585)
16. McLaughlin (566)
17. McConnel (565)
18. McRae (506)
19. McCarty (499)
20. McPherson (489)
21. McLeod, McCloud (477)
22. McBride (472)
23. McCall (460)
24. McCallister (460)
25. McKay (442)
26. McCormick (440)
27. McMillen (435) not McMullen
28. McKnight (413)
29. McKinsey (410)
30. McGill (388)

Many more Mac names are in this census, but
these are the most popular. (see chart in book for
locations and more Mac names).

The following pages will give further evidence
of the location of Mac and O names in Ireland,
Scotland, and America. For the convenience of
researchers we have included names as found in
the 1659 census, the 1890 birth index of Ireland,
and the 1790 U.S. census. For the latter, we
have used the ‘most numerous’ names listed in
that census”

New 4th edition just released:
The Book of Irish Families, great & small


“The movement of the Irish ‘O’ and Mac names into
America presents us with a new area of study.
Relatively few ‘O’ names are found in the 1790
census listed as ‘most numerous’. O’Bryan and
O’Neal are two notable exceptions, and the variant
spellings they included at that time were Orneal;
O’Nail; O’Nale; Obirant; OBryon; Obryant; O’Brian;
and O’Brien, among several others. While there are
many more Mac names on the census, (including Irish,
Scottish and Scots-Irish names). Many Mac names
dropped the prefix in America as well. Those who
dropped the Mac were recorded as completely
different families in the 1790 census. They may
today unknowingly still be hiding their original
names !

Dropping the ‘O’
Likewise, plenty of ‘O’ names are found on this
early census – without the ‘O’. Sullivan, Sewlovan,
Sylivan, Sullivern, Neal, Quinn, Quine, Quynn, Regan,
Ryan, Rian, Whelan, Boyle, Brady, Calahan, Kellyhan,
Connolly, Donoho, Dougherty, Donovan, Donally, Flanagan,
Hogan, Kelly, Kenedy, Laughlin, Lowry, Lynch, and
Malone jump from the pages quickly and most were
originally ‘O’ names.
Spellings are numerous for these names. That is a
common finding. When researching mid-western American
settlement in the 1700’s, I found several examples that
confirm the variety of spellings. O’Bryan written as
O’Bune; McCormick written as M’Corniss; McGee written
as Mcgui; O’Hara written as Orra; O’Sullivan written
as WSullivan and McMullen written as M. Mullen. All
of these examples are from the Spanish regime in America.
Just another generation of name changes for the Irish
and Scots! (per Irish Settlers on the American Frontier: Missouri Irish.)”

About the author
Mike O’Laughlin is the worlds most published author
in the field of Irish Family History. (Author of 50 books;
20 CD’s, DVD’s, & videos: 700 articles; 2 newsletters;
300 broadcasts; Publisher of rare works in Irish and English;
and singer in the Irish language,’Sean Nós’ style)

Mikes online Irish hedge school has six fields of study
including: Genealogy; History; Irish-America; Language;
Traditional Song; and video shorts.
The 4th edition of his Master Volume to Irish Family
History and research is now available at:

About Mike

Mike is the worlds most published author in his field, with over 40 books, 700 articles, two newsletters, a blog, 200 podcasts and 170 videos. He also publishes rare books like "The Annals of Ireland by the Four Masters" and Keatings "History of Ireland". Mike also sings in the Irish (Gaeilge) Language, with 3 albums to his credit. Mike descends from the O’Loughlins of Kilfenora, County Clare, and the O’Donahues of Glenflesk, County Kerry and also bears Sullivan, Buckley, Kilmartin, Llewellyn and Kelliher roots. He has led tours to Ireland and maintains a 3,000 volume Irish library.
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