Ireland 1841 vs 2021

The map above looks at the change in demographics on the island of Ireland in 1841 (just before the Great potatoes famine) and 2021/22 the date of the last censuses for the two parts of the island today.

In 1841 the island was firmly part of the United Kingdom of Great Britain and Ireland. Today the island is divided between the Republic of Ireland and Northern Ireland (part of the United Kingdom).

More about the comparison below:

Religion	Northern Ireland	Republic of Ireland	Combined Total	Share of Total
Catholic	805,151	3,540,412	4,345,563	61.52%
No Religion / Not stated	361,512	1126062	1,487,574	21.06%
Protestant	580,616	216099	796,715	11.28%
Other Christian	130,385	144066.3	274,451	3.89%
Islam	10,870	81,930	92,800	1.31%
Other religion	14,654	51673	66,327	0.94%
Total	1,903,188	5,160,242	7,063,430	100%

* Note protestants includes members of the Church of Ireland, Presbyterians, and Methodists among others.

The Baseline: 1841 Census (Pre-Famine Ireland)

Population (Island-wide): ~8.2 million (the highest ever recorded).

What it looked like:

• Predominantly rural and agrarian, with about 75% of people living in the countryside.
• The majority were Roman Catholic (~80%), with Protestant minorities (mainly Anglican Church of Ireland and Presbyterian) concentrated in Ulster (especially in what became Northern Ireland).
• Irish was widely spoken, particularly in the west and southwest.

The Great Famine (1845–1852) and Its Aftermath

Catastrophic demographic collapse:

• ~1 million died from starvation and disease.
• Another ~1 million emigrated (mostly to Britain, the U.S., and Canada).

By the 1851 Census:

• Population fell to 6.5 million.

Long-term effects:

• Continuous emigration persisted for over a century.
• Rural depopulation was especially severe in Connacht, Munster, and parts of Leinster.
• Ulster (especially Belfast) became more urban and industrialized.

Late 19th Century: Industrial vs. Rural Divergence

• Ireland as a whole:
  • Continued population decline – 4.4 million by 1911.
• Regional split:
  • Ulster (especially Belfast): growing, industrial (linen, shipbuilding), Protestant-majority.
  • Rest of Ireland: shrinking, heavily Catholic, agricultural, dependent on emigration.
• Language: The Irish language declined sharply due to famine deaths and English dominance in education and economy.

Partition (1921) and Diverging Paths

• 1921–1922: Ireland was partitioned into:
  • Northern Ireland (6 counties) – remained in the United Kingdom.
  • Irish Free State (later the Republic of Ireland) – gained independence.

Demographics around 1926

• Northern Ireland: ~1.25 million
  • ~33% Catholic, ~65% Protestant (mainly Presbyterian and Anglican).
• Irish Free State: ~3 million
  • ~93% Catholic, ~7% Protestant.

Mid-20th Century (1930s–1960s): Stagnation vs. Stability

• Republic of Ireland:
  • Population hit its low point (~2.8 million in 1961).
  • Massive emigration to Britain; limited industrial growth.
  • Very high birth rates, but offset by outmigration.
• Northern Ireland:
  • Population relatively stable (~1.4–1.5 million).
  • Slower emigration due to British economic integration.
  • Persistent sectarian divide, Catholics a minority (around 35%).

Late 20th Century (1970s–1990s): The Troubles and Change

• Northern Ireland:
  • “The Troubles” (1969–1998) caused moderate emigration (both Catholic and Protestant).
  • Catholic proportion of the population rose slowly due to higher birth rates.
  • 1991 Census: ~38% Catholic, ~54% Protestant.
• Republic of Ireland:
  • Economic modernization began (1970s–1990s).
  • Natural increase started outpacing emigration by the 1990s.
  • Population began growing again after over a century of decline.

21st Century: Recovery, Immigration, and Religious Change

Republic of Ireland

• Population growth:
  • 2002: ~3.9 million
  • 2016: ~4.8 million
  • 2024: ~5.3 million (highest since before the Famine).
• Key drivers:
  • Economic boom (“Celtic Tiger” period, 1995–2007).
  • Large-scale immigration from Eastern Europe (especially Poland), the UK, and Africa.
  • Falling birth rates but sustained natural increase.
• Religion:
  • Rapid secularization, the Catholic share fell from ~90% (1991) to ~69% (2022).
  • Rise of “no religion” and small Protestant, Muslim, and Orthodox communities.
• Urbanization:
  • Over one-third of the population now lives in the Greater Dublin Area.

Northern Ireland

• Population:
  • 2001: ~1.7 million
  • 2021: ~1.9 million.
• Religious balance:
  • 2021 Census: Catholics 45.7%, Protestants 43.5%.
  • For the first time in modern history, Catholics became the largest single community, a major demographic milestone.
• Migration:
  • Immigration from the EU and beyond since the 2000s.
  • Internal migration to cities like Belfast and Derry/Londonderry.
• Identity:
  • Increasing number of people identifying as “Northern Irish” rather than strictly British or Irish.

Sources:

• Religion in Northern Ireland
• Religion in the Republic of Ireland
• “The judgement of God on an indolent and unself-reliant people”?: The impact of the Great Irish Famine on Ireland’s religious demography
• Ireland