O'Brien family name history and map
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O'Brien in 1911 Ireland
The 1911 Census recorded 24,564 people named O'Brien in Ireland, about 0.56% of everyone living in the country at the time and the 7th most common surname overall. The name was split fairly evenly between men and women: 12,137 men and 12,397 women. (A small number, 30, had no sex recorded.)
Counties with O'Brien in Ireland
Cork had the largest share of O'Briens, 19.4% (4,754 people). Next came Dublin (3,423), Tipperary (2,738), Limerick (2,690) and Clare (1,667).
O'Brien average age in 1911
The average O'Brien in 1911 was 29.3 years old, 28.8 for men and 29.7 for women; almost exactly in line with the national averages of 29.6 for men and 30.5 for women. That low figure reflects just how many children there were in Edwardian Ireland, along with high infant mortality and the limits of public health at the time. For comparison, average life expectancy in Ireland today is around 83.
O'Brien literacy in 1911
Of the O'Briens whose literacy was recorded, 78.7% could both read and write, 3.4% could read but not write, and 17.9% could do neither. The figures were much the same for men and women. Bear in mind these figures include young children; the census itself only counted people aged nine and over when calculating illiteracy, on the grounds that it was unfair to label a child illiterate before they'd had a chance to learn.
O'Brien common first names
The most common male names were John (1,817), Patrick, Michael, James and Thomas; the same five names that topped the list nationally. For women it was Mary (2,170), followed by Bridget, Margaret, Ellen and Catherine.
O'Brien occupations in 1911
The most common entry on an O'Brien's census form was "Scholar"; 20.8% (5,103) were children at school. Among the rest, the most common occupations were farmer (13.7%), general labourer (4.9%), farm labourer (4%) and domestic servant (3.9%). Grouped by sector, agriculture accounted for 18.5% of all O'Briens, followed by domestic service, general labourers and retail & commerce.
What religion is O'Brien?
O'Briens were overwhelmingly Roman Catholic, 97.6% of them. The remainder were mostly Anglican (1.4%) and Presbyterian (0.1%).
Visitor Notes
Review type for post source and surnames source type not found
Added by
Pete F
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O'Brien statistics (1911)
Number: 24,564
Rank: 7
Average Age: 29
O'Brienin the USA (2020)
Number: 115,547
Rank: 261
Note: If there were less than 100 in the USA census it will show as zero.
