How Ireland changed — a century of census data
Two censuses, 96 years apart. In 1926 Ireland had a population of 2.97 million. By 2022 the population had grown to 5.15 million — but growth skipped the counties that started with the least.
The map that moved
In 1926 the most populous counties were Dublin, Cork and Mayo. Since then the fastest-growing counties have been Kildare, Meath, Dublin and Wicklow. The pattern is not random. It tracks economic opportunity, transport links, and the long shadow of agricultural dependency.
The agricultural trap — why Connacht emptied
Agricultural occupations varied enormously by county in 1926: from 3% of persons aged 12 and over in Dublin to 47% in Leitrim, against 29.7% nationally. The national figure hides a county-level story that is even starker.
In 1926, agricultural occupations accounted for 47% of persons aged 12 and over in Leitrim, 46% in Roscommon, 46% in Mayo, 45% in Cavan. These were subsistence farming communities on poor land. They had few alternative industries and well-worn emigration routes to Britain and America. 4 of the 5 counties that lost population between 1926 and 2022 were among the 5 most agricultural in 1926 — one of the clearest patterns in the data.
Kildare, by contrast, had just 27% in agricultural occupations in 1926 — and grew by 327% over the century. Dublin, at 3%, grew by 188%. The counties that had already moved away from farming by 1926 were the ones that grew.
- Leitrim (47% ag → −37% pop): The starkest case. Poor land, no urban centre, no rail links in key areas. Emigration ran without break from the Famine through to the 1980s and beyond.
- Mayo (46% ag → −20% pop): Lost 34,720 people between 172,690 in 1926 and 137,970 in 2022. Castlebar and Westport grew while rural areas hollowed out.
- Roscommon (46% ag → −16% pop): Down 13,297 from its 1926 base of 83,556. The county had a railway — then lost it, deepening isolation.
- Kildare (27% ag → +327% pop): The commuter belt effect. Naas, Maynooth, Celbridge, Newbridge — all grew as Dublin expanded along the M7 and rail corridors.
- Meath (35% ag → +251% pop): Navan, Ashbourne, Dunboyne — all absorbed Dublin overspill. From the 1990s onward, agricultural land converted to housing at scale.
Dublin's hidden housing crisis — 1926
The 1926 census recorded one-room dwellings as 26.1% of permanent private households in Dublin, against 7.5% nationally — the highest rate of any county. These were the tenements of the inner city: families of six or eight living in a single room in houses that had once been Georgian townhouses. The tuberculosis epidemic of the 1930s, the Iveagh Trust, and the Corporation housing schemes of the 1940s and 50s all responded to what the 1926 census recorded.
The housing crisis of 2026 has different causes — shortage rather than overcrowding, the periphery rather than the centre. But the 1926 map of Dublin's one-room dwellings is a reminder that the city has faced acute housing stress before. It took a generation of public investment to resolve it.
Map one-room dwellings by county 1926 →The Gaeltacht in 1926
In 1926, Irish speaker rates clustered in the west — Galway (47.4%), Mayo (36.8%), Donegal (34.4%), Kerry (33.0%) and Clare (30.3%). These were living language communities, not heritage designations. All five also had an agricultural share above the national 29.7%.
Dublin recorded 7.8% Irish speakers in 1926, the lowest of any county — the capital of a state that had made Irish a constitutional language in 1922. The census shows a language whose survival depended on rural communities.
Religion in 1926
The 1926 census recorded Ireland as 92.6% Roman Catholic — but the Protestant geography was more varied than the national figure suggests. Wicklow had the highest Church of Ireland (including Protestant) share at 15.0% (8,662 people), followed by Cavan (12.3%), Dublin (10.6%) and Monaghan (9.8%). These patterns reflect plantation histories and the concentration of the Anglo-Irish landowning class.
By 2022, the Church of Ireland (including Protestant) nationally made up 2.6% of the population, down from 5.5% in 1926 — a decline driven by emigration of Protestant families and a wider shift in religious self-identification.
Who was living in Ireland in 1926?
96.6% of Ireland's 1926 population was born in Ireland. The largest foreign-born group came from Great Britain — 49,354 people, likely including returned emigrants and the families of those who had moved between the islands before independence. A further 35,132 were born in Northern Ireland, reflecting how new the border was. 9,405 were born in the United States — a visible trace of the return flow from emigrant communities in Boston, New York and Chicago.
Explore the full century on the map
IrelandInsights maps all four 1926 county metrics alongside Census 2022 data. Every county shows its 1926 figure next to its 2022 comparison — agriculture, Irish speakers, population change, and housing on a single live map.
1926 census overview → · Population growth → · Rural Ireland today →
Vol. 1 — Population · Vol. 2 — Occupations · Vol. 3 — Religion & Birthplaces · Vol. 8 — Irish Language · All 1926 volumes
National Archives — search household returns · CSO Then and Now 1926–2022 · CSO Census 2022
Explore the live map
The charts above are snapshots; the live map below is the full dataset for every county and electoral division. Hover any area for the underlying figures, switch geography levels, and compare with related metrics.