📊 Add long-run Ireland migration data

[edomt]

Written by Claude Fable 5 — @edomt at the wheel.

Part of https://github.com/owid/owid-issues/issues/2470 (child of https://github.com/owid/owid-issues/issues/2464).

What this adds

A new dataset migration/2026-08-05/ireland_net_migration with two indicators for Ireland, 1871–2025: net migration, in people and as a share of the population. The whole series covers the same area — the 26 counties of today's Republic — so independence in 1922 does not create a break.

The series is OWID-maintained (processing_level: major), combining three sources from the Central Statistics Office and its predecessors:

• 1871–1926 — average yearly net emigration for each period between censuses, from the 1926 Census General Report (Volume X, p. 19), hand-entered with asserts tying the values to the report's own printed totals. The report estimates net emigration as a census residual; civil registration of births and deaths began in 1864, so 1871 is the earliest possible start.
• 1926–1951 — net migration totals per intercensal period from the 2022 census results (table F1005), divided by period length.
• From 1951 — the CSO's annual estimates (table PEA15, years ending in April).

Before 1951, each year carries its intercensal period's average, so the series is stepped. Shares divide by interpolated census populations before 1951 and the CSO's annual population estimates after — all denominators come from the dataset's own snapshots.

Notes

• The metadata explains the construction period by period, the sign convention, and the 1911–1926 caveat (the residual method counts First World War deaths abroad as emigration, and the period includes the post-independence departures).
• No gross immigration/emigration indicators — deliberately net-only, per the scoping discussion.

🤖 Generated with Claude Code

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chart-diff: ❌

• 0/1 reviewed charts
• Modified: 0/0
• New: 0/1
• Rejected: 0
• Data changes: 0
• Metadata changes: 0

data-diff: ✅ no differences

No differences found.

Automatically updated datasets matching excess_mortality|covid|fluid|flunet|country_profile|garden/ihme_gbd/2019/gbd_risk are not included. Run locally with etl diff REMOTE data/ --include <dataset> --verbose.

Edited: 2026-08-05 14:35:29 UTC
Execution time: 22.87 seconds

[edomt]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

Reviewed commit: a1e2e3c886

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